Clot retrieval devices

ABSTRACT

A clot retrieval device for removing clot from a blood vessel including a plurality of ring elements comprising a plurality of struts forming one or more closed cells having one or more crown elements and attached together by connecting tethers at connection points, a plurality of openings through which clot may pass and enter the device, each opening being disposed between respective ring elements. Each ring element can be self-expandable from a collapsed configuration to an expanded configuration wherein a radial force biases the ring elements toward the expanded configuration. At least one of the crown element terminates in an apex away from a center axis of the device.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 16/544,423, filed Aug. 19, 2019, which is acontinuation application of U.S. patent application Ser. No. 15/226,389filed Aug. 2, 2016, which is a continuation application of U.S. patentapplication Ser. No. 13/829,684 filed Mar. 14, 2013, now U.S. Pat. No.9,433,429 issued Sep. 6, 2016. The entire contents of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of distalmechanical thrombectomy, more particularly, to a self-expandablemechanical clot retrieval device used in the treatment of acute ischemicstroke and pulmonary embolism in a patient. The retrieval device is ofextremely small size delivered through an intravascular microcatheterand meticulously designed to remain in a collapsed state while advancingthrough the microcatheter to remove thrombus or embolus from the blockedarteries.

BACKGROUND

Acute ischemic stroke remains one of the major causes of death anddisability worldwide. It refers to stroke caused by thrombosis orembolism creating an acute blockage in vasculature that stops flow ofblood and deprives the surrounding brain tissue of oxygen. In theabsence of oxygen, the brain cells of the immediate area begin to dieand release a cascade of toxic chemicals that threaten brain tissue inthe surrounding area.

Similarly, pulmonary embolism is a common and potentially fatalcondition, creating a sudden blockage in a lung artery caused by anynaturally occurring embolus traveling through the arteries of the lungand occluding a small artery that stops the flow of blood and deprivesthe surrounding lung tissue of oxygen. In the absence of oxygen, thelung tissues in the immediate area succumb to lysis as they are unableto process sufficient oxygen into the blood.

Importantly, both acute ischemic stroke and pulmonary embolism can beavoided and treated by removing the acute blockage and restoring bloodflow to the affected area. In recent years, significant advances havebeen made to prevent ischemic stroke and pulmonary embolism throughendovascular procedures involving the use of distal mechanical clotretrieval devices on the end of catheters to manually retract clot andfragments of clot.

Generally, the distal mechanical devices are delivered endovascularlyand advanced by guidewire and microcatheter until the device is locateddistal of the clot where it expands. Thus force is applied to the distalsurface of the clot to dislodge it from the artery wall where it iscaught and retracted proximally by the retrieval device.

Despite continuous advances made in the art of distal mechanicalthrombectomy, there is still much room for improvement in effectivelyremoving acute blockage particularly in engaging and retracting thrombusor embolus from extremely small vasculature. The present invention is anefficient and meticulous approach to improve upon the distal mechanicalthrombectomy.

SUMMARY

Various aspects of the present invention concern a self-expandablemechanical clot retrieval device that effectively and reliably removesthrombus or embolus from blocked vasculature. It is designed variouslyto dislodge, engage and retract blood clot from extremely small andtortuous vasculature. The retrieval device comprises an elongate memberand a plurality of ring elements. The ring elements may comprise aplurality of struts and crowns interconnected by a tether formed at adistal end of the elongate member or may be a separate componentattached thereto. In one aspect, at least one tether connects each ringelement to the elongate member to restrain the ring element in acollapsed configuration during delivery of the retrieval device throughan intravascular microcatheter. The tether connecting the ring elementto the elongate member disengages when the retrieval device ispositioned at the occluded site and the microcatheter is retracted toallow the self-expandable ring elements to reach an expandedconfiguration. Preferably, the self-expandable ring elements are formedof shape memory material such as Nitinol.

Additional aspects of the present invention concern methods of using themechanical clot retrieval device described in the previous paragraph. Itis used in the treatment of acute ischemic stroke and pulmonary embolismin a patient. The method of removing the blood clot from a blockedartery includes advancing a self-expandable mechanical clot retrievaldevice having an elongate member and a plurality of self-expandable ringelements arranged at a distal end of the elongate member through thevasculature to a blockage site in the artery. The retrieval devicebypasses the clot and is positioned distal to the clot to allow theself-expandable ring elements to reach an expanded configuration inorder to engage the clot within expanded ring elements and is proximallyretracted from the artery. The method may include retracting theexpanded ring elements proximally into a guide catheter or amicrocatheter.

In a first embodiment of the invention the clot retrieval devicecomprises an elongate member and a plurality of clot engaging elementsat a distal end of the elongate member, the clot engaging elements beingself expandable and having a retracted delivery configuration and anexpanded deployed configuration; and a biasing element for biasing theclot engaging elements into a retracted delivery configuration againstthe elongate member; the biasing element being releasable to allow theclot engaging elements to expand into the deployed configuration.

The second embodiment of the invention comprises a method of retrievinga clot comprising the steps of: (1) providing an elongate member and aplurality of clot engaging elements at a distal end of the elongatemember, the clot engaging elements having a retracted configuration andan expanded configuration: (2) providing a biasing element for retainingthe clot engaging elements in the retracted configuration; (3) advancinga microcatheter across a clot; (4) advancing the elongate member withthe clot engaging elements in a retracted configuration through themicrocatheter so that at least some of the clot engaging elements aredistal of the clot; (5) releasing the biasing so that the clot engagingelements expand to the expanded configuration; (6) engaging the clotengaging elements with a clot; and (7) using the clot engaging elements,drawing the clot into a retrieval element.

A third embodiment of the invention comprises a luminal prosthesisdevice comprising: an elongate member and a plurality of luminalprosthetic elements at a distal end of the elongate member; the luminalprosthetic elements being self expandable and having a retracteddelivery configuration and an expanded deployed configuration; and abiasing element for biasing the luminal prosthetic elements into aretracted delivery configuration against the elongate member; thebiasing element being releasable to allow the luminal prostheticelements to expand into the deployed configuration.

A fourth embodiment of the invention comprises a clot retrieval devicecomprising: an elongate member and a plurality of clot engaging elementsat a distal end of the elongate member, the clot engaging elements beingself expandable and having a retracted delivery configuration, aretracted deployed configuration and a fully expanded configurations;and providing a release element for biasing the clot engaging elementsin at least one retracted configuration; activation of the releaseelement allowing the clot engaging elements to expand into the fullyexpanded configuration.

In one variation of this embodiment the diameter of the clot engagementelements in the retracted delivery configuration is smaller than thediameter of the clot engagement elements in the retracted deployedconfiguration and the diameter of the clot engagement elements in theretracted deployed configuration is smaller than the diameter of theclot engagement elements in the fully expanded configuration.

In another variation of this embodiment a release element is configuredto bias the clot engaging elements in a retracted deployedconfiguration. The release element may be integral with the clotengagement elements. The release element may be integral with elongatemember. The release element may be connected to either the clotengagement elements, the elongate member or to both. The release elementmay comprise; a snap element, a restraining element, a tether, aninterlocking element, an overlapping element of the clot engagementelement, an abutment element, a connector element, a housing element, apair of interacting elements, or a limiting element configured to limitat least one degree of expansion movement.

In another variation of this embodiment the clot engagement elementcomprises a plurality of struts and said release element is configuredto limit relative movement between at least a pair of said struts. Inanother variation of this embodiment the release element is configuredto limit relative movement between the clot engagement element and theelongate member. The elongate member may be configured to activate therelease element.

In another variation of this embodiment the device comprises anactivation element said activation element configured to affect therelease of the release element. The activation element may comprise anelongate tube, an elongate member, or a tether.

A fifth embodiment of the invention comprises a clot retrieval devicecomprising: an elongate member and a first clot engaging element and asecond clot engaging element the first clot engaging element distal ofthe second clot engaging element, the clot engaging elements being selfexpandable and having a sheathed delivery configuration, a deployedconfiguration and a fully expanded configurations; and providing atleast one release element for biasing the clot engaging elements in thedeployed configuration; activation of the at least one release elementallowing the clot engaging elements to expand into the fully expandedconfiguration.

In one variation of this embodiment the sheathed configuration comprisessheathing within the lumen of a microcatheter. In another variation ofthis embodiment the unsheathing the clot engaging elements allows theclot engaging elements to assume the unsheathed configuration. Inanother variation of this embodiment the diameter of the clot engagingelements in the deployed configuration is greater than the diameter ofthe clot engaging elements in the sheathed configuration. In anothervariation of this embodiment the first clot engagement element assumesthe expanded configuration while the second clot engaging element is inthe deployed configuration.

A sixth embodiment of the invention comprises a method for retrieval ofa clot comprising the steps of: (1) providing a clot retrieval devicethe clot retrieval device comprising an elongate member and a pluralityof clot engaging elements at a distal end of the elongate member, theclot engaging elements having a retracted configuration, a partiallyexpanded configuration and an expanded configuration; (2) providing abiasing element for limiting the expansion of the clot engagingelements; (3) advancing a microcatheter across a clot; (4) advancing theelongate member with the clot engaging elements in a retractedconfiguration through the microcatheter so that at least some of theclot engaging elements are distal of the clot; (5) retracting themicrocatheter so as to unsheathe at least one clot engaging element, (6)activating the biasing element so as to trigger the expansion of atleast one of said clot engagement elements to the expandedconfiguration, (7) retracting the clot retrieval device and the clotinto a proximal retrieval element.

In one variation of this embodiment the method comprises the step ofretracting the microcatheter also comprises the step of expanding the atleast one clot engagement element to the partially expandedconfiguration. In another variation of this embodiment the step ofactivating the biasing element comprises the step of applying anactivation force to the biasing element.

In another variation of this embodiment the step of activating thebiasing element comprises the step of applying a compressive, tensile,twisting or radial force to the biasing element.

In another variation of this embodiment the method comprises the step ofproviding a plurality of clot engagement elements configured such thatin the partially expanded configuration a flow lumen extends through thecentre of said clot engagement elements, said lumen being larger thanthe diameter of the microcatheter and smaller than the diameter of thevessel.

In another variation of this embodiment the method comprises the step ofholding the clot retrieval device steadfast in the vessel for a dwelltime period the dwell time period comprising at least one minute.

A seventh embodiment of the invention comprises a retrieval device forremoving occlusive clot from the vasculature the retrieval devicecomprising: an elongate member and an expandable body connected to theelongate member, the expandable body comprising a plurality ofself-expanding clot engaging elements, each clot engaging elementcomprising a plurality of struts and a plurality of crowns arranged toform at least one ring, at least one of said plurality of crownscomprising an integral connection to an adjacent ring, a spacing betweenat least two of said clot engaging elements said spacing comprising avariable spacing in use.

In one variation of this embodiment the at least one integral connectioncomprises a monolithic connection. The at least one integral connectionmay comprise a connection to a crown of an adjacent ring of the sameclot engaging element. The at least one integral connection may comprisea connection to a crown of a ring of an adjacent engaging element. Theat least one integral connection may comprise a connection to theelongate member. In another variation of this embodiment the at leastone of said plurality of crowns comprises an unconnected crown.

In another variation of this embodiment the a pair of adjacent crowns ofsaid expandable body comprise a pair of unconnected crown, the first ofsaid pair of adjacent crowns comprising a proximally facing crown andthe second of said pair of adjacent crowns comprising a distally facingcrown. The first crown of said pair of adjacent crowns may be located ona first clot engaging element and the second crown of said pair ofadjacent crowns may be located on a second clot engaging element.

In another variation of this embodiment the clot engaging elements arearranged in series. In another variation of this embodiment the clotengaging elements are arranged in series.

In another variation of this embodiment the clot engagement elements arespaced apart. The spacing between at least two of said clot engagingelements may vary during delivery. The spacing between at least two ofsaid clot engaging elements may vary during engagement with the clot.The spacing between at least two of said clot engaging elements may varyduring clot disengagement with the vessel wall. The spacing between atleast two of said clot engaging elements may vary during withdrawal ofthe clot through the vasculature. The spacing between at least two ofsaid clot engaging elements may vary during removal of the clot anddevice into the lumen of a retrieval catheter. The spacing between atleast two of said clot engaging elements may vary across the diameter ofthe clot engaging elements.

An eighth embodiment of the invention comprises a retrieval device forremoving occlusive clot from the vasculature comprising: an elongatemember and an expandable body connected to the elongate member, theexpandable body comprising an collapsed delivery configuration and anexpanded configuration, the expandable body comprising a plurality ofself-expanding clot engaging elements, cut from a tube in a monolithicstructure, each clot engaging element comprising a plurality of strutsand a plurality of crowns arranged to form a ring, at least one pair ofadjacent clot engaging elements being spaced apart by a plurality ofconnector elements, the pair of adjacent clot engaging elements and theplurality of connectors configured to create a plurality of clotengaging cells, the plurality of connectors comprising a plurality ofhelical strut.

In one variation of this embodiment the plurality of clot engaging cellsare configured to scaffold outwardly so as to create a flow lumenthrough the clot. The plurality of clot engaging cells may be configuredto urge clot ingress through the cell openings so that the clot isinterlaced with the plurality of engaging cells.

In another variation of this embodiment the helical struts extendcircumferentially through an angle of at least 25 degrees. In anothervariation of this embodiment the helical struts extend circumferentiallythrough an angle of at least 40 degrees. In another variation of thisembodiment the helical struts extend circumferentially through an angleof at least 50 degrees. In another variation of this embodiment thehelical struts extend axially a distance of at least 500 micrometers. Inanother variation of this embodiment the helical struts extend axially adistance of at least 750 micrometers. In another variation of thisembodiment the helical struts extend axially a distance of at least 900micrometers.

In another variation of this embodiment the tube from which theexpandable body is cut has a diameter larger than the diameter of theexpandable body in the collapsed delivery configuration. The tube fromwhich the expandable body is cut may have a diameter equal to or smallerthan the expanded diameter of the expandable body.

A ninth embodiment of the invention comprises a mechanical clotretrieval device for use in a blood artery, comprising an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the artery and the proximal end extends exterior ofthe artery; and a plurality of self-expandable ring elements configuredat the distal end of the elongate member, wherein each ring element,comprising a plurality of struts, is interconnected by ring connectingtethers and is delivered through an intravascular microcatheter in acollapsed configuration inside the artery, wherein the ring elementscomprise a radial force biasing ring elements toward an expandedconfiguration, wherein the radial force is absorbed by the elongatemember in the collapsed configuration, wherein the microcatheter isretracted proximally allowing the ring elements reach the expandedconfiguration.

In one variation of this embodiment each strut comprises a crownelement. The crown element may comprise an engagement member and a fixedtab. The crown element may comprise an engagement member and anengagement hook. The crown element may comprise an engagement member anda connector. The crown element may comprise an engagement member and anengagement tab. The crown element may engage a neighboring crown elementin a snap-fit mechanism.

In another variation of this embodiment the snap-fit mechanism restrainsthe ring elements in the collapsed configuration. The ring elements inthe collapsed configuration may be substantially parallel along thelongitudinal axis of the elongate member. In another variation of thisembodiment the device comprises a proximal fixed collar configuredproximally of the ring elements. In another variation of this embodimentthe device further comprises a push tube attached to the proximal fixedcollar.

In another variation of this embodiment the device further comprises adistal moveable collar configured distally of the ring elements. Inanother variation of this embodiment the device comprises a balloon. Inanother variation of this embodiment the balloon is delivered in adeflated state. In another variation of this embodiment the devicefurther comprises a ball element. In another variation of thisembodiment the device further comprises a pair of pull tethers havingdistal and proximal ends. In another variation of this embodiment thedistal ends are connected to the most proximal ring element. In anothervariation of this embodiment the distal ends are attached to theconnector. In another variation of this embodiment the distal ends areattached to the engagement tab.

In another variation of this embodiment the distal ends are attached tothe distal movable collar. In another variation of this embodiment theproximal ends extend exterior of the artery. The proximal ends may bemanually pulled proximally to disengage the snap-fit mechanism. Theproximal ends may be attached to the elongate member. In anothervariation of this embodiment the balloon is inflated to disengage thesnap-fit mechanism. In another variation of this embodiment the ballelement is manually retracted proximally to disengage the snap-fitmechanism.

A tenth embodiment of the invention comprises a mechanical clotretrieval device for use in an artery, comprising an elongate memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; and a plurality of self-expandable ring elements configured atthe distal end of the elongate member, wherein each ring element,comprising a plurality of struts, is attached to the elongate member byconnecting tethers and is delivered through an intravascularmicrocatheter in a collapsed configuration, wherein the ring elementscomprise a radial force biasing the ring elements toward an expandedconfiguration, wherein the radial force is absorbed by the elongatemember in the collapsed configuration, wherein the microcatheter isretracted proximally allowing the ring elements to reach the expandedconfiguration.

In one variation of this embodiment each strut comprises a crownelement. In another variation of this embodiment the proximally facingcrown element is a ring proximal crown and distally facing crown elementis a ring distal crown. The ring proximal crown may be attached to theelongate member by connecting tethers. The crown element may be engagedwith the elongate member in a snap-fit mechanism. The snap-fit mechanismrestrains the ring elements in the collapsed configuration. The elongatemember is manually retracted to disengage the snap-fit mechanism. Inanother variation of this embodiment the elongate member is attached toat least one ring element in the expanded configuration.

A eleventh embodiment of the invention comprises a mechanical clotretrieval device for use in an artery, comprising an elongate memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; and a plurality of self-expandable ring elements configured atthe distal end of the elongate member, wherein each ring elementcomprising a plurality of struts is interconnected by ring connectingtethers and is delivered through an intravascular microcatheter in acollapsed configuration, wherein the ring elements comprise a radialforce biasing the ring elements toward an expanded configuration,wherein the microcatheter is retracted allowing the ring elements toreach the expanded configuration.

In one variation of this embodiment each strut comprises a crownelement. The crown element may be attached to the elongate member by abonding agent. The bonding agent restrains the ring elements in thecollapsed configuration. The bonding agent may be dissolved in vivoallowing the ring elements reach the expanded configuration. The radialforce may be absorbed by the bonding agent.

In another variation of this embodiment the crown element is attached tothe elongate member by a resorbable covering. The re-absorbable coveringrestrains the ring elements in the collapsed configuration. There-absorbable covering may be dissolved in vivo allowing the ringelements to reach the expanded configuration. The radial force may beabsorbed by the re-absorbable covering. In another variation of thisembodiment the device comprises a pair of pull tethers having distal andproximal ends. The distal ends of said tethers are attached to most theproximal ring element. The proximal ends of said tethers extend exteriorof the artery.

An twelfth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end, a proximal end and a plurality of radial pins,wherein the distal end extends interior of the artery and the proximalend extends exterior of the artery; and a plurality of self-expandablering elements configured at the distal end of the elongate member,wherein each ring element, comprising a plurality of struts, is advancedthrough an intravascular microcatheter in a collapsed configuration,wherein the ring elements comprise a radial force biasing the ringelements toward an expanded configuration, wherein the radial force isabsorbed by radial pins in the collapsed configuration, wherein themicrocatheter is retracted allowing the ring elements to reach theexpanded configuration.

In one variation of this embodiment the radial pin has an engagementmember. In another variation of this embodiment each strut comprises acrown element. The crown element may comprise a plurality of eyelets. Inanother variation of this embodiment the distally facing eyelet engageswith the radial pin. The distally facing eyelet may fasten the ringelements to the elongate member.

In another variation of this embodiment the proximally facing eyeletengages with the radial pins in a snap-fit mechanism. In anothervariation of this embodiment the snap-fit mechanism restrains the ringelements in the collapsed configuration. In another variation of thisembodiment the engagement member is dissolved in vivo to disengage thesnap-fit mechanism. In another variation of this embodiment theengagement member is dissolved in vivo allowing the ring elements toreach the expanded configuration.

An thirteenth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end, a proximal end, an outer tube having a plurality ofslots and a retractable inner core wire, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a plurality of self-expandable ring elements configured at thedistal end of the elongate member, wherein each ring element, comprisinga plurality of struts, is interconnected by ring connecting tethers andis delivered through an intravascular microcatheter in a collapsedconfiguration, wherein the ring elements comprise a radial force biasingthe ring elements toward an expanded configuration, wherein the radialforce is absorbed by the inner core wire in the collapsed configuration,wherein the microcatheter is retracted proximally allowing the ringelements to reach the expanded configuration.

In one variation of this embodiment each strut comprises a crown elementhaving an eyelet. In another variation of this embodiment a tether isadvanced out of the slot to loop through the eyelet and folds back intothe slot to loop around the retractable inner core wire. The tether mayengage the ring elements with the elongate member in a tether-loopmechanism. In another variation of this embodiment the tether-loopmechanism restrains the ring elements in the collapsed configuration.

In another variation of this embodiment the retractable inner core wireis manually retracted proximally to disengage the tether-loop mechanism.The retractable inner core wire may be advanced out of each slot to loopthrough each eyelet and folds back into the slot to loop inside theouter tube. The retractable inner core wire may engage the ring elementswith the elongate member in a tether-loop mechanism.

In another variation of this embodiment the tether-loop mechanismrestrains the ring elements in the collapsed configuration. In anothervariation of this embodiment the retractable inner core wire is manuallyretracted proximally to disengage the tether-loop mechanism.

An fourteenth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end, a proximal end and a tube lumen having a pluralityof slots, wherein the distal end extends interior of the artery and theproximal end extends exterior of the artery; and a plurality ofself-expandable ring elements configured at the distal end of theelongate member, wherein each ring element, comprising a plurality ofstruts, is interconnected by ring connecting tethers and is deliveredthrough an intravascular microcatheter in a collapsed configuration,wherein the ring elements comprise a radial force biasing the ringelements toward an expanded configuration, wherein the microcatheter isretracted proximally allowing the ring elements to reach the expandedconfiguration.

In one variation of this embodiment each strut comprises a crown elementhaving an eyelet. In another variation of this embodiment the devicefurther comprises a plurality of tethers, having distal ends that extendinterior of the tube lumen and proximal ends that extend exterior of theartery. Each tether may be advanced through a slot to loop around theeyelet and folded back into the slot attached to the distal end of theelongate member. Each tether may engage the ring elements with theelongate member in a tether-loop mechanism. The tether-loop mechanismmay restrain the ring elements in the collapsed configuration. Eachtether may be broken to disengage the snap-fit mechanism allowing ringelements to reach the expanded configuration.

An fifteenth embodiment of the invention comprises a mechanical clotretrieval device for use in a blood artery, comprising an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the artery and the proximal end extends exterior ofthe artery; a proximal collar attached to an abutment tube; and aplurality of self-expandable ring elements configured at the distal endof the elongate member, wherein each ring element, comprising aplurality of struts, is attached to the elongate member by connectingtethers and is advanced through an intravascular microcatheter in acollapsed configuration, wherein the ring elements comprise a radialforce biasing the ring elements toward an expanded configuration,wherein the microcatheter is retracted allowing the ring elements toreach the expanded configuration.

In one variation of this embodiment each strut comprises a crownelement. In another variation of this embodiment the device furthercomprises a plurality of tethers. Each tether may be looped around thering element and is attached to the elongate member.

Each tether may engage the ring elements with the elongate member in atether-loop mechanism. The radial force may be absorbed by thetether-loop mechanism. The tether-loop mechanism may restrain the ringelements in the collapsed configuration. In another variation of thisembodiment the elongate member may be manually retracted proximally todisengage the tether-loop mechanism.

A sixteenth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a plurality of collars configured at the distal end of theelongate member; and a plurality of self-expandable ring elementsconfigured at the distal end of the elongate member, wherein each ringelement is configured between two collars, wherein each ring element,comprising a plurality of struts, is interconnected by ring connectingtethers and is delivered through an intravascular microcatheter in acollapsed configuration, wherein the ring elements comprise a radialforce biasing the ring elements toward an expanded configuration,wherein the radial force is absorbed by the collars in the collapsedconfiguration, wherein the microcatheter is retracted allowing the ringelements reach the expanded configuration.

In one variation of this embodiment the collar is bevel shaped or thecollar is recess shaped or the collar is a shaped engagement collar orthe collar has a plurality of holes or the collar has a plurality ofdove tail grooves.

In one variation of this embodiment each strut comprises a crownelement. In one variation of this embodiment the crown element has a tabextending axially and radially inward. The crown element may have a pinextending axially and radially inward. The crown element may have ashaped tab extending axially and radially inward and the tab may bebevel shaped. The tab may be square shaped. The tab may engage with thecollar in a collar mechanism.

In another variation of this embodiment the collar mechanism engages thering elements with the elongate member. The collar mechanism mayrestrain the ring elements in the collapsed configuration. In anothervariation of this embodiment the elongate member is manually retractedproximally to disengage the collar mechanism.

In another variation of this embodiment the pin engages with the hole ina collar mechanism. In another variation of this embodiment the collarmechanism engages the ring elements with the elongate member. In anothervariation of this embodiment the collar mechanism restrains the ringelements in the collapsed configuration. In another variation of thisembodiment the elongate member is manually retracted proximally todisengage the collar mechanism.

In another variation of this embodiment the shaped tab engages with thedove tail groove in a collar mechanism. In another variation of thisembodiment the collar mechanism engages the ring elements with theelongate member. In another variation of this embodiment the collarmechanism restrains the ring elements in the collapsed configuration. Inanother variation of this embodiment the elongate member is manuallyretracted proximally to disengage the collar mechanism.

A seventeenth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a proximal collar; and a self-expandable ring element configuredat the distal end of the elongate member, wherein the ring element,comprising a plurality of struts, is delivered through an intravascularmicrocatheter in a collapsed configuration, wherein the ring elementcomprises a radial force biasing the ring element towards an expandedconfiguration, wherein the radial force is absorbed by the proximalcollar in the collapsed configuration, wherein the microcatheter isretracted allowing the ring element to reach the expanded configuration.

In one variation of this embodiment each strut comprises a crown elementhaving a tab extending axially and radially inward. In another variationof this embodiment the tab engages with the proximal collar in a collarmechanism. In another variation of this embodiment the collar mechanismengages the ring element with the elongate member. In another variationof this embodiment the collar mechanism restrains the ring element inthe collapsed configuration. In another variation of this embodiment theelongate member is manually retracted proximally to disengage the collarmechanism.

A eighteenth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end, a proximal end and inner lumen having a pluralityof openings, wherein the distal end extends interior of the artery andthe proximal end extends exterior of the artery; and a plurality ofself-expandable ring elements configured at the distal end of theelongate member, wherein each ring element, comprising a plurality ofstruts, is interconnected by ring connecting tethers and is deliveredthrough an intravascular catheter in a collapsed configuration, whereinthe ring elements comprise a radial force biasing the ring elementstoward an expanded configuration, wherein the microcatheter is retractedallowing the ring elements reach the expanded configuration.

In one variation of this embodiment each strut comprises a crown elementand an engagement tab. In one variation of this embodiment the devicefurther comprises a plurality of tethers having proximal ends extendexterior of the inner lumen. In one variation of this embodiment eachtether is advanced out of each opening and is wrapped around theengagement tab in an eyelet mechanism. In one variation of thisembodiment the eyelet mechanism engages the ring elements with theelongate member. In one variation of this embodiment the eyeletmechanism restrains the ring elements in the collapsed configuration.

In one variation of this embodiment the radial force is absorbed by theeyelet mechanism. In one variation of this embodiment the tethers aremanually pulled proximally to disengage the eyelet mechanism.

A nineteenth embodiment of the invention comprises a mechanical clotretrieval device for use in a blood artery, comprising an elongatemember having a distal end, a proximal end and a plurality of raisedtabs, wherein the distal end extends interior of the artery and theproximal end extends exterior of the artery; and a plurality ofself-expandable ring elements configured at the distal end of theelongate member, wherein each ring element, comprising a plurality ofstruts, is interconnected by ring connecting tethers and is deliveredthrough an intravascular microcatheter in a collapsed configuration,wherein the ring elements comprise a radial force biasing the ringelements towards an expanded configuration, wherein the radial force isabsorbed by the raised tabs in the collapsed configuration, wherein themicrocatheter is retracted allowing the ring elements to reach theexpanded configuration.

The variations described in association with each of the embodiments 1through to 19 can be applied to the 20.sup.th through to the 36.sup.thembodiments (below) and are hereby incorporate as variations to each ofthe 20.sup.th through to the 36.sup.th embodiments.

A twentieth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end, a proximal end, a plurality of engagement diametersand a plurality of disengagement diameters, wherein the distal endextends interior of the artery and the proximal end extends exterior ofthe artery; a proximal abutment tube; and a plurality of self-expandablering elements configured at the distal end of the elongate member,wherein each ring element, comprising a plurality of struts, isinterconnected by ring connecting tethers and is delivered through anintravascular microcatheter in a collapsed configuration, wherein thering elements comprise a radial force biasing the ring elements towardan expanded configuration, wherein the radial force is absorbed byengagement diameters in the collapsed configuration, wherein themicrocatheter is retracted allowing the ring elements to reach theexpanded configuration. Each strut may comprise a crown element having aC-shaped engagement tab extending radially inward. The C-shapedengagement tab engages with the engagement diameter to restrain the ringelements along the elongate member. The C-shaped engagement tab engageswith the engagement diameter to restrain the ring element in thecollapsed configuration. In one variation of this embodiment proximalaxial movement of the elongate member disengages the ring element at thedisengagement diameter.

A twenty first embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end, a proximal end and an inner wire, wherein thedistal end extends interior of the artery and the proximal end extendsexterior of the artery; a proximal abutment tube; and a plurality ofself-expandable ring elements configured at the distal end of theelongate member, wherein each ring element, comprising a plurality ofstruts, is interconnected by ring connecting tethers and is deliveredthrough an intravascular microcatheter in a collapsed configuration,wherein the ring elements comprise a radial force biasing the ringelements toward an expanded configuration, wherein the radial force isabsorbed by the elongate member in the collapsed configuration, whereinthe microcatheter is retracted allowing the ring elements to reach theexpanded configuration.

A twenty second embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising: an elongate memberhaving a distal end, a proximal end and an inner lumen with a pluralityof slots, wherein the distal end extends interior of the artery and theproximal end extends exterior of the artery; a proximal collar; and aplurality of self-expandable ring elements configured at the distal endof the elongate member, wherein each ring element, comprising aplurality of struts, is interconnected by ring connecting tethers and isdelivered through an intravascular microcatheter in a collapsedconfiguration, wherein the ring elements comprise a radial force biasingthe ring elements toward an expanded configuration, wherein the radialforce is absorbed by slots in the collapsed configuration, wherein themicrocatheter is retracted allowing the ring elements to reach theexpanded configuration.

A twenty third embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising: an elongate memberhaving a distal end, a proximal end and a plurality of monofilaments,wherein the distal end extends interior of the artery and the proximalend extends exterior of the artery; a proximal collar; and a pluralityof self-expandable ring elements configured at the distal end of theelongate member, wherein each ring element, comprising a plurality ofstruts, is interconnected by ring connecting tethers and is deliveredthrough an intravascular microcatheter in a collapsed configuration,wherein the ring elements comprise a radial force biasing the ringelements in an expanded configuration, wherein the radial force isabsorbed by monofilaments in the collapsed configuration, wherein themicrocatheter is retracted allowing the ring elements to reach theexpanded configuration.

A twenty fourth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising: an elongate memberhaving a distal end, a proximal end and a plurality of inactivated cuffsconfigured at the distal end of the elongate member, wherein the distalend extends interior of the artery and the proximal end extends exteriorof the artery; a tube; and a plurality of self-expandable ring elementsconfigured over the inactivated cuffs, wherein each ring element,comprising a plurality of struts, is interconnected by ring connectingtethers and is delivered through an intravascular microcatheter in acollapsed configuration, wherein the ring elements comprise a radialforce biasing the ring elements towards an expanded configuration,wherein the microcatheter is retracted allowing the ring elements toreach the expanded configuration.

A twenty fifth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an elongate memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a proximal collar; a bumper tube; and a plurality ofself-expandable ring elements configured at the distal end of theelongate member, wherein each ring element, comprising a plurality ofstruts, is interconnected by ring connecting tethers and is deliveredthrough an intravascular microcatheter in a collapsed configuration;wherein the ring elements comprise a radial force biasing the ringelements toward an expanded configuration, wherein the microcatheter isretracted allowing the ring elements to reach the expandedconfiguration.

A twenty sixth embodiment of the invention comprises a mechanical clotretrieval device for use vasculature, comprising: an elongate memberhaving a distal end, a proximal end and a plurality of restraining loopsconfigured at the distal end of the elongate member, wherein the distalend extends interior of the artery and the proximal end extends exteriorof the artery; and a plurality of self-expandable ring elementsconfigured at the distal end of the elongate member, wherein each ringelement, comprising a plurality of struts, is connected to therestraining loop by connecting tethers, wherein the ring elements have aradial force biasing the ring elements toward an expanded configuration,wherein the radial force is absorbed by the restraining loops in acollapsed configuration.

A twenty seventh embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising: an elongate memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end that extends exterior of theartery; a bumper tube; a proximal collar; and a plurality ofself-expandable ring elements configured at the distal end of theelongate member, wherein each ring element comprising a plurality ofstruts is interconnected by ring connecting tethers, wherein the ringelements comprise a radial force biasing the ring elements toward anexpanded configuration, wherein the radial force is absorbed by theelongate member in a collapsed configuration.

A twenty eighth embodiment of the invention comprises a mechanical clotretrieval device for use in a tortuous vessel, comprising an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the vessel and the proximal end extends exterior ofthe vessel; and a plurality of self-expandable ring elements configuredat the distal end of the elongate member, wherein each ring element,comprising a plurality of struts, is interconnected by ring connectingtethers and is delivered through an intravascular microcatheter in acollapsed configuration, wherein the ring elements have a radial forcebiasing the ring elements toward an expanded configuration, wherein theradial force is absorbed by the microcatheter in the collapsedconfiguration, wherein the microcatheter is retracted allowing the ringelements to reach the expanded configuration.

A twenty ninth embodiment of the invention comprises a mechanical clotretrieval device for use in a tortuous vessel, comprising an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the vessel and the proximal end extends exterior ofthe vessel; a plurality of self-expandable ring elements having a firstdiameter and a second diameter, wherein each ring element, comprising aplurality of struts, is interconnected by ring connecting tethers and isdelivered through an intravascular microcatheter in a collapsedconfiguration; and a control strut having distal end attached to mostproximal ring element and proximal end attached to the elongate memberby adhesive bonds, wherein the ring elements have a radial force biasingthe ring elements toward an expanded configuration, wherein the radialforce is absorbed by the microcatheter in the collapsed configuration,wherein the microcatheter is retracted proximally allowing the ringelements to reach the expanded configuration.

A thirtieth embodiment of the invention comprises a mechanical clotretrieval device for use in a tortuous vessel, comprising an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the vessel and the proximal end extends exterior ofthe vessel; and a plurality of self-expandable ring elements, whereineach ring element, comprising a plurality of struts, is interconnectedby ring connecting tethers and is delivered through an intravascularmicrocatheter in a collapsed configuration; and wherein the ringelements have a radial force biasing the ring elements towards anexpanded configuration, wherein the radial force is absorbed by themicrocatheter in the collapsed configuration, wherein the microcatheteris retracted proximally allowing the ring elements reach the expandedconfiguration.

A thirty first embodiment of the invention comprises a mechanical clotretrieval device for use in a tortuous vessel, comprising: an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the vessel and the proximal end extends exterior ofthe vessel; a plurality of self-expandable ring elements configured atthe distal end of the elongate member, wherein each ring elementcomprises a plurality of struts and is delivered through anintravascular microcatheter in a collapsed configuration; and aplurality of ring connecting tethers having distal and proximal ends,wherein the distal ends are connected to the ring element and theproximal ends are attached to the elongate member, wherein the ringelements have a radial force biasing the ring elements towards anexpanded configuration, wherein the radial force is absorbed by themicrocatheter in the collapsed configuration, wherein the microcatheteris retracted allowing the ring elements to reach the expandedconfiguration.

A thirty second embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an activation tetherhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a distal collar, wherein the distal end of the activation tetheris attached to the distal collar; and a plurality of self-expandablering elements configured at the distal end of the activation tether,wherein each ring element, comprising a plurality of struts, isinterconnected by bridges and is delivered through a microcatheter in acollapsed configuration, wherein the ring elements have a radial forcebiasing the ring elements towards an expanded configuration, wherein theradial force is absorbed by the microcatheter in the collapsedconfiguration, wherein the microcatheter is retracted allowing the ringelements reach the expanded configuration.

A thirty third embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an activation tetherhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a distal collar, wherein the distal end of the activation tetheris attached to the distal collar; and a self-expandable ring elementconfigured at the distal end of the activation tether, wherein the ringelement comprises a plurality of struts and is delivered through amicrocatheter in a collapsed configuration, wherein the ring element hasa radial force biasing the ring element toward the expandedconfiguration, wherein the radial force is absorbed by the microcatheterin the collapsed configuration, wherein the microcatheter is retractedallowing the ring element to reach the expanded configuration.

A thirty fourth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an activation tetherhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a distal collar, wherein the distal end of the activation tetheris attached the distal collar; a self-expandable ring element configuredat the distal end of the activation tether, wherein the ring elementcomprises a plurality of struts and is delivered through a microcatheterin a collapsed configuration; and a pair of removal tethers havingdistal ends attached to the ring element and proximal ends that extendexterior of the artery, wherein the ring element has a radial forcebiasing the ring element towards an expanded configuration, wherein theradial force is absorbed by the microcatheter in the collapsedconfiguration, wherein the microcatheter is retracted allowing the ringelement to reach the expanded configuration.

A thirty fifth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising an activation tetherhaving a distal end and a proximal end, wherein the distal end extendsinterior of the artery and the proximal end extends exterior of theartery; a couple of collars; a couple of ring elements configured at thedistal end of the activation tether, wherein each ring elementcomprising a plurality of struts and is delivered through amicrocatheter in a collapsed configuration; and a pair of removaltethers having distal ends attached to the ring element and proximalends attached to the collar, wherein the ring elements have a radialforce biasing the ring elements toward an expanded configuration,wherein the radial force is absorbed by the microcatheter in thecollapsed configuration, wherein the microcatheter is retracted allowingthe ring elements to reach the expanded configuration.

A thirty sixth embodiment of the invention comprises a mechanical clotretrieval device for use in vasculature, comprising a pair of activationtethers having distal ends extending interior of the artery and proximalends extending exterior of the artery; a distal collar, wherein distalends of the activation tether are attached to the distal collar; and aplurality of self-expandable ring elements configured at distal ends ofthe activation tethers, wherein the each ring element, comprising aplurality of struts, is interconnected by bridges and is deliveredthrough an intravascular microcatheter in a collapsed configuration,wherein the ring elements have a radial force biasing the ring elementstowards an expanded configuration, wherein the radial force is absorbedby the microcatheter in the collapsed configuration, wherein themicrocatheter is retracted allowing the ring elements to reach theexpanded configuration.

The mechanical clot retrieval device in any of the preceding embodimentsmay comprise a ring element made of shape memory material. Themechanical clot retrieval device in any of the preceding embodiments maycomprise a ring element is made of Nitinol. The mechanical clotretrieval device in any of the preceding embodiments may comprise aretrieval device that is made of shape memory material. The mechanicalclot retrieval device in any of the preceding embodiments may comprise aretrieval device that is partly made of shape memory material.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example withreference to the accompanying drawings, in which:

FIG. 1 a is a diagram illustrating a typical occlusive clot in acerebral artery;

FIG. 1B is an enlarged view of a detail of FIG. 1 a;

FIGS. 2 a-2 h are diagrams illustrating the insertion of a guidewire andthe deployment of a clot retrieval device of the invention;

FIGS. 3 a-3 e illustrate a clot retrieval device according to oneembodiment of the invention;

FIGS. 4 a-4 d illustrate steps involved in using the device of FIGS. 3 a-3 d;

FIGS. 5 a-5 e illustrate another clot retrieval device of the invention;

FIGS. 6 a-6 f illustrate a further clot retrieval device of theinvention;

FIGS. 7 a-7 e illustrate another clot retrieval device of the invention;

FIGS. 8 a-8 d illustrate a further clot retrieval device of theinvention;

FIGS. 9 a-9 d illustrate another clot retrieval device of the invention;

FIGS. 10 a-10 d illustrate a further clot retrieval device of theinvention;

FIGS. 11 a-11 h illustrate another clot retrieval device of theinvention;

FIGS. 12 a-12 c illustrate a further clot retrieval device of theinvention;

FIGS. 13 a-13 f illustrate another clot retrieval device of theinvention;

FIGS. 14 a-14 c illustrate a further clot retrieval device of theinvention;

FIGS. 15 a-15 c illustrate a method for using a clot retrieval device ofthe invention;

FIGS. 16 a-16 d illustrate another method for using a clot retrievaldevice of the invention;

FIGS. 17 a-17 d illustrate a further clot retrieval device of theinvention;

FIGS. 18 a-18 d illustrate another clot retrieval device of theinvention;

FIGS. 19 a-19 d illustrate a further clot retrieval device of theinvention;

FIGS. 20 a-20 b illustrate another clot retrieval device of theinvention;

FIGS. 21 a-21 f illustrate a further clot retrieval device of theinvention;

FIGS. 22 a-22 d illustrate a method for using a clot retrieval device ofthe invention;

FIGS. 23 a-23 c illustrate a mechanism used in a clot retrieval deviceof the invention;

FIGS. 24 a-24 c illustrate a further clot retrieval device of theinvention;

FIGS. 25 a-25 k illustrate another clot retrieval device of theinvention;

FIGS. 26 a-26 d illustrate a further clot retrieval device of theinvention;

FIGS. 27 a-27 b illustrate another clot retrieval device of theinvention;

FIGS. 28 a-28 b illustrate a further clot retrieval device of theinvention;

FIGS. 29 a-29 h illustrate a method for using a clot retrieval device ofthe invention;

FIGS. 30 a-30 e illustrate another clot retrieval device of theinvention;

FIGS. 31 a-31 e illustrate a further clot retrieval device of theinvention;

FIGS. 32 a-32 d illustrate another clot retrieval device of theinvention;

FIGS. 33 a-33 g illustrate a further clot retrieval device of theinvention;

FIGS. 34 a-34 j illustrate another clot retrieval device of theinvention;

FIGS. 35 a-35 b illustrate a further clot retrieval device of theinvention;

FIGS. 36 a-36 d illustrate another clot retrieval device of theinvention;

FIGS. 37 a-37 i illustrate a further clot retrieval device of theinvention;

FIGS. 38 a-38 d illustrate another clot retrieval device of theinvention;

FIGS. 39 a-39 d illustrate a further clot retrieval device of theinvention;

FIGS. 40 a-40 e illustrate a method for using a clot retrieval device ofthe invention;

FIGS. 41 a-41 d illustrate another method for using a clot retrievaldevice of the invention;

FIGS. 42 a-42 g illustrate a further clot retrieval device of theinvention;

FIGS. 43 a-43 h illustrate another clot retrieval device of theinvention;

FIGS. 44 a-44 b illustrate a further clot retrieval device of theinvention;

FIG. 45 illustrates another clot retrieval device of the invention;

FIG. 46 illustrates a further clot retrieval device of the invention;

FIG. 47 illustrates another clot retrieval device of the invention;

FIGS. 48 a-48 f illustrate a further clot retrieval device of theinvention;

FIGS. 49 a-49 f illustrate another clot retrieval device of theinvention;

FIGS. 50 a-50 g illustrate a further clot retrieval device of theinvention;

FIGS. 51 a-51 f illustrate another clot retrieval device of theinvention;

FIGS. 52 a-52 d illustrate a further clot retrieval device of theinvention;

FIGS. 53 a-53 f illustrate a method for using a clot retrieval device ofthe invention;

FIGS. 54 a-54 h illustrate another method for using a clot retrievaldevice of the invention;

FIG. 55 illustrates another clot retrieval device of the invention;

FIG. 56 illustrates a further clot retrieval device of the invention;

FIG. 57 illustrates another clot retrieval device of the invention;

FIG. 58 illustrates a further clot retrieval device of the invention;

FIG. 59 illustrates a further clot retrieval device of the invention;

FIG. 60 illustrates another clot retrieval device of the invention;

FIGS. 61 a-61 c illustrate a further clot retrieval device of theinvention;

FIGS. 62 a-62 b illustrate another clot retrieval device of theinvention;

FIGS. 63 a-63 b illustrate a further clot retrieval device of theinvention;

FIGS. 64 a-64 b illustrate another clot retrieval device of theinvention;

FIGS. 65 a-65 d illustrate a further clot retrieval device of theinvention;

FIGS. 66 a-66 c illustrate another clot retrieval device of theinvention;

FIGS. 67 a-67 b illustrate a further clot retrieval device of theinvention;

FIGS. 68 a-68 b illustrate another clot retrieval device of theinvention; and

FIGS. 69 a-69 b illustrate a further clot retrieval device of theinvention.

DETAILED DESCRIPTION

Specific embodiments of the present invention are now described indetail with reference to the figures, wherein similar reference numbersindicate identical or functionality similar elements. The terms “distal”or “proximal” are used in the following description with respect to aposition or direction relative to the treating physician. “Distal” or“distally” are a position distant from or in a direction away from thephysician. “Proximal” or “proximally” or “proximate” are a position nearor in a direction toward the physician.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description of the invention is in the contextof treatment of blood arteries such as the carotid and lung arteries,the invention may also be used in any other vessels where it is deemeduseful.

As shown generally in FIGS. 1 a-1 b and 2 a-2 h , an obstructive clot 2is occluding a cerebral artery 1 and a guidewire 3 is inserted into theartery 1 using conventionally known techniques. The guidewire 3 isadvanced across the clot 2 and then a microcatheter 4 is advanced overthe guidewire 3 to a location distal to the clot 2. The mechanical clotretrieval device 10 of the present invention is advanced through themicrocatheter 4 and across the clot 2. The retrieval device 10 has anelongate member 11 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, and aplurality of ring elements 12 configured at the distal end of theelongate member. The ring elements 12 are self-expandable from acollapsed configuration to an expanded configuration and comprise aradial force that biases the ring elements 12 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the elongate member 11. When the retrieval device 10 isadvanced through the microcatheter 4, the ring elements are in thecollapsed configuration substantially parallel to the longitudinal axisof the elongate member 11. Each ring element 12 comprising a pluralityof struts 13 is made of self expanding material such as nitinol and isinterconnected by ring connecting tethers 14. The microcatheter 4 isretracted after the retrieval device 10 is positioned within or distalof the clot 2 to allow ring elements 12 to deploy and expand. When thering elements 12 deploy and expand, the struts 13 engage or capture theclot 2 in the ring elements 12 and the retrieval device 10 is retractedproximally out of the artery 1.

FIGS. 3 a-3 d illustrates one of the preferred embodiments of amechanical clot retrieval device 20 of the present invention. Theretrieval device 20 has an elongate member 21 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, and a plurality of ring elements 22 configured at thedistal end of the elongate member 21. The ring elements 22 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements22 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by the elongate member 21. Each ringelement 22 comprising a plurality of struts 23 is made of shape memorymaterial Nitinol and is interconnected by ring connecting tethers 24.Each strut 23 has a crown element 27 with an engagement member 29 and afixed tab 30. The crown element 27 holds the neighboring crown element27 in a snap-fit mechanism 28 to restrain the ring elements 22 in thecollapsed configuration substantially parallel to the longitudinal axisof the elongate member 21. Two pull tethers 25 which have distal endsthat are attached to most proximal ring element 22, and proximal endsthat extend exterior of the artery for maneuvering and control by thephysician, are present. The snap-fit mechanism 28 restrains theretrieval device 20 in the collapsed configuration when advancingthrough a microcatheter 4.

FIGS. 4 a-4 d shows a method of using the retrieval device 20 inaccordance with the preferred embodiment as shown in FIGS. 3 a-3 d . Aguidewire (not shown) is inserted in the cerebral artery 1 and isadvanced distally across an obstructive clot 2. A microcatheter 4 isadvanced over the guidewire to a location proximal to the clot and thenthe retrieval device 20 of the present invention is advanced through themicrocatheter 4 to the clot in the collapsed configuration. Theretrieval device 20 has an elongate member 21 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, and a plurality of ring elements 22 configured at thedistal end of an elongate member 21. The ring elements 22 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements22 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by the elongate member 21. When theretrieval device 20 is advanced through the microcatheter 4, the ringelements are in collapsed configuration substantially parallel to thelongitudinal axis of the elongate member 21. Each ring element 22comprises a plurality of struts 23 and is made of shape memory materialnitinol and is interconnected by ring connecting tethers 24. Themicrocatheter 4 is retracted when the retrieval device 20 is positionedwithin or distal of the clot 2 to allow ring elements 22 to reach theexpanded configuration. The pull tethers 25 attached to the retrievaldevice 20 allow the physician to manually disengage the snap-fitmechanism 28. The ring elements 22 engage or capture the clot 2 from thedistal surface of the clot 2 and retract the clot 2 proximally towardsthe microcatheter 4. The microcatheter 4 is re-advanced to reduce theexpanded configuration of the proximal end of the device 20 in order toretrieve it more easily from the artery 1.

FIGS. 5 a-5 d shows a mechanical clot retrieval device 40 of the presentinvention which is a slight variant of the embodiment of the retrievaldevice as shown in FIGS. 3 a-3 d . The retrieval device 40 has anelongate member 41 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 42 configured at the distal end of theelongate member 41, and a proximal collar 51. The ring elements 42 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements42 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by the elongate member 41. Each ringelement 42 comprising a plurality of struts 43 and is made of shapememory material Nitinol and is interconnected by ring connecting tethers44. Also present are a pair of pull tethers 45, having distal ends whichare attached to the most proximal ring element 42 and the proximal endsare attached to the elongate member 41. Each strut 43 has a crownelement 47 with an engagement member 49 and an engagement hook 50. Eachcrown element 47 holds the neighboring crown element 47 in a snap-fitmechanism 48 which restrains the ring elements 42 in the collapsedconfiguration substantially parallel to the longitudinal axis of theelongate member 41. The snap-fit configuration 48 restrains theretrieval device 40 in the collapsed configuration when advancingthrough the microcatheter 4.

Another embodiment of the mechanical clot retrieval device of thepresent invention, which is similar to the one shown in FIGS. 3 a-3 d ,is illustrated in FIGS. 6 a-6 f The retrieval device 60 has an elongatemember 61 having a distal end that extends interior of the artery and aproximal end that extends exterior of the artery, and a plurality ofring elements 62 configured at the distal end of the elongate member 61.The ring elements 62 are self-expandable from a collapsed configurationto an expanded configuration and comprise a radial force that biases thering elements 62 toward the expanded configuration. In the collapsedconfiguration, the radial force is absorbed by the elongate member 61.Each ring element 62, comprising a plurality of struts 63, is made ofshape memory material Nitinol and is interconnected by ring connectingtethers 64. Each strut 63 has a crown element 67 with an engagementmember 68. Each engagement member 68 holds the neighboring crown element67 in a snap-fit mechanism which restrains the ring elements 62 in thecollapsed configuration substantially parallel to the longitudinal axisof the elongate member 61. A pair of pull tethers 65 are attached,having distal ends which are attached to each connector (not labeled) ofthe crown element 67, and proximal ends which extend exterior of theartery for manipulation and control by the physician. The snap-fitmechanism restrains the retrieval device 60 in the collapsedconfiguration as it is advancing through the microcatheter 4. The pulltethers 65 may be used to manually disengage the snap-fit mechanism andallow the retrieval device 60 reach the expanded configuration.

Another embodiment of the mechanical clot retrieval device of thepresent invention, which is largely similar to the one shown in FIGS. 3a-3 d , is illustrated in FIGS. 7 a-7 f The retrieval device 80 has anelongate member 81 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, and aplurality of ring elements 82 configured at the distal end of theelongate member 81. The ring elements 82 are self-expandable from acollapsed configuration to an expanded configuration and comprise aradial force that biases the ring elements 82 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the elongate member 81. Each ring element 82, comprising aplurality of struts 83, is made of shape memory material Nitinol and isinterconnected by ring connecting tethers 84. Each strut 83 has a crownelement 87 with an engagement member 89 and an engagement tab 88. Eachcrown element 87 holds the neighboring crown element 87 in a snap-fitmechanism which restrains the ring elements 82 in the collapsedconfiguration substantially parallel to the longitudinal axis of theelongate member 81. A pair of pull tethers 85 is attached, having distalends which are attached to each engagement tab 88 of the crown element87, and proximal ends which extend exterior of the artery formanipulation and control by the physician. The snap-fit mechanismrestrains the retrieval device 80 in the collapsed configuration as itis advancing through the microcatheter 4. The pull tethers 85 may beused to manually disengage the snap-fit mechanism and allow theretrieval device 80 to reach the expanded configuration.

Another preferred embodiment of the mechanical clot retrieval device 100of the present invention is illustrated in FIGS. 8 a-8 d . The retrievaldevice 100 includes an elongate member 101 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 102 arranged at the distalend of the elongate member 101, a fixed proximal collar 111 and a distalmoveable collar 110. The ring elements 102 are self-expandable from acollapsed configuration to an expanded configuration and comprise aradial force that biases the ring elements 102 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the elongate member 101. Each ring element 102 comprising aplurality of struts 103 is made of shape memory material nitinol and isinterconnected by ring connecting tethers 104. Each strut 103 has a hooklock 107 with first lock 108 and second lock 109. Each hook lock 107holds the neighboring hook lock 107 in a snap-fit mechanism to restrainthe ring elements 102 in the collapsed configuration substantiallyparallel to the axis of the elongate member 101. There are pair of pulltethers 105 attached, having distal ends which are attached to thedistal collar 110, and proximal ends that extend exterior of the arteryfor maneuvering and control by the physician. The snap-fit mechanismrestrains the retrieval device in the collapsed configuration whenadvancing through the microcatheter 4. The distal collar 110 is pulledproximally by the pull tether 105 to manually disengage and allow ringelements 102 reach an expanded configuration.

FIGS. 9 a-9 d shows a mechanical clot retrieval device 120 of thepresent invention, which is a slight variant of the embodiment of theretrieval device 100 as shown in FIGS. 8 a-8 d ; the only difference isuse of a balloon 125 in place of the distal moveable collar 110. Theretrieval device 120 has an elongate member having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 122 configured at the distalend of the elongate member 121, a proximal collar 126 and a balloon 125.The ring elements 122 are self-expandable from a collapsed configurationto an expanded configuration and have a radial force that biases thering elements 122 toward the expanded configuration. In the collapsedconfiguration, the radial force is absorbed by the elongate member 121.Each ring element 122 comprises a plurality of struts 123 and is made ofshape memory material nitinol and is interconnected by ring connectingtethers 124. Each strut 123 has a hook lock 127 with a first lock 128and a second lock 109. Each hook lock 127 holds the neighboring hooklock 127 in a snap-fit mechanism to restrain the ring elements 122 inthe collapsed configuration. The balloon 125 is in a collapsed statewhen the device 20 is advanced through the microcatheter 4. The balloon125 is inflated to disengage and allow ring elements 122 to reach theexpanded configuration.

Another embodiment of a mechanical clot retrieval device 140 of thepresent invention is largely similar to the one shown in FIGS. 8 a-8 d ,and is shown in FIGS. 10 a-10 d ; with the main difference being the useof a ball element 145 in place of the distal movable collar 110. Theretrieval device 140 has an elongate member 141 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 142 configured at the distalend of the elongate member 141, a proximal collar 150 attached to a pushtube 146, and a ball element 145. The ring elements 142 areself-expandable from a collapsed configuration to an expandedconfiguration and feature a radial force that biases the ring elements142 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by the elongate member 141. Each ringelement 142, comprising a plurality of struts 143, is made of shapememory material nitinol and is interconnected by ring connecting tethers144. Each strut 143 has a hook lock 147 with a first lock 148 and asecond lock 149. Each hook lock 147 holds the neighboring hook lock 147in a snap-fit mechanism to restrain the device 140 in the collapsedconfiguration. The ball element 145 is manually pulled proximallythrough the device 140 to force apart the ring elements 142 whichsubsequently form the expanded configuration.

FIGS. 11 a-11 h shows another preferred embodiment of a mechanical clotretrieval device of the present invention. The retrieval device 160includes an elongate member 161 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, and a plurality of ring elements 162 attached to the elongatemember 161 by connecting tethers 164 at connection points 165. The ringelements 162 are self-expandable from a collapsed configuration to anexpanded configuration and comprise a radial force that biases the ringelements 162 toward the expanded configuration. In the collapsedconfiguration, the radial force is absorbed by the elongate member 161.Each ring element 162, comprising a plurality of struts 163, is made ofshape memory material nitinol. Each strut 163 features a crown element169, which includes a proximal ring crown 167 and a distal ring crown166. The connecting tether 164 connects the proximal ring crown 167 withthe elongate member 161. The crown element 169 engages with the elongatemember 161 in a snap-fit mechanism to restrain the ring elements 162 inthe collapsed configuration. The snap-fit mechanism 168 restrains theretrieval device 160 in the collapsed configuration as it advancesthrough a microcatheter 4. The microcatheter 4 is retracted proximallyto disengage and allow the ring elements 162 to reach the expandedconfiguration. The elongate member 161 is manually retracted todisengage the snap-fit mechanism.

Another embodiment of a mechanical clot retrieval device of the presentinvention is illustrated in FIGS. 12 a-12 c . A guidewire is insertedinside a cerebral artery 501 using conventional techniques. Theguidewire is advanced across an obstructive clot 502 and then anintravascular microcatheter 504 is advanced over the guidewire to alocation proximal to the clot 502. The retrieval device 520 has anelongate member having a distal end that extends interior of the arteryand a proximal end that extends exterior of the artery, and a pluralityof ring elements 522 configured at the distal end 526 of the elongatemember 521. The ring elements 522 are self-expandable from a collapsedconfiguration to an expanded configuration and have a radial force thatbiases the ring elements 522 towards the expanded configuration. Eachring element 522, comprising a plurality of struts 523, is made of shapememory material nitinol and is interconnected by ring connecting tethers524. Each strut 523 has a crown element 527 attached to the elongatemember 521 by a bonding agent 528 to restrain the ring elements 522 inthe collapsed configuration. The radial force is absorbed by the bondingagent 528 to restrain the retrieval device 520 in the collapsedconfiguration when the device is advancing through the microcatheter504. The bonding agent 528 is dissolved in vivo to disengage and allowthe ring elements 522 to reach the expanded configuration. The devicehas a pair of pull tethers 525, having distal ends which are attached tomost proximal ring element 522 and proximal ends that extend out of theartery for maneuvering and control by the physician.

FIGS. 13 a-13 f shows a slight variant embodiment of a mechanical clotretrieval device of the present invention, largely similar to the oneshown in FIGS. 12 a-12 c . The difference between the two is the use ofa soluble covering 548 in place of the bonding agent 528. The retrievaldevice 540 has an elongate member, having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, and a plurality of ring elements 542 configured at the distalend 546 of the elongate member 541. The ring elements 542 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force biasing the ring elements 542towards the expanded configuration. Each ring element 542, comprising aplurality of struts 543, is made of shape memory material nitinol and isinterconnected by ring connecting tethers 544. Each strut 543 has acrown element 547 attached to the elongate member 541 by a re-absorbablecovering 548 to restrain the ring elements 542 in the collapsedconfiguration. The radial force is absorbed by the re-absorbablecovering 548 to restrain the retrieval device 540 in the collapsedconfiguration when it is advancing through the microcatheter (notshown). The re-absorbable covering 548 is dissolved in vivo to disengageand allow the ring elements 542 to reach the expanded configuration. Thedevice features a pair of pull tethers 545, having distal ends which areattached to the most proximal ring element 542 and proximal ends thatextend out of the artery for maneuvering and control by the physician.

Another preferred embodiment of a mechanical clot retrieval device ofthe present invention is shown in FIGS. 14 a-14 c . The retrieval device1020 includes an elongate member 1021 having a distal end that extendsinterior of the artery, a proximal end that extends exterior of theartery and a plurality of radial pins 1028, and a plurality of ringelements 1022 configured at the distal end 1026 of the elongate member1021. The ring elements 1022 are self-expandable from a collapsedconfiguration to an expanded configuration and comprise a radial forcethat biases ring elements 1022 towards the expanded configuration. Eachring element 1022, comprising a plurality of struts, is made of shapememory material nitinol and each strut 1023 contains a crown element1027 with an eyelet 1024. The distal eyelet 1024 engages with the radialpin 1028 by an engagement element 1029 to fasten the ring elements tothe elongate member, whereas proximal eyelets 1024 engage withengagement members 1029 of radial pins 1028 in a snap-fit mechanism torestrain the ring elements 1022 in the collapsed configuration. The ringelements 1022 may be connected to the elongate member 1021 by ringconnecting tethers (not shown). The snap-fit mechanism restrains theretrieval device 1020 in the collapsed configuration when advancingthrough the microcatheter (not shown).

FIGS. 15 a-15 c and 16 a-16 d show a method for using a mechanical clotretrieval device 1040 in accordance with the preferred embodiment shownin FIGS. 14 a-14 c . A guidewire 1003 is inserted in a cerebral artery1001 and is advanced across an obstructive clot 1002. An intravascularmicrocatheter 1004 is advanced over the guidewire 1003 to a locationproximal to the clot 1002 and then a mechanical clot retrieval device1004 is advanced through the microcatheter 1004 to the clot 1002 in acollapsed configuration. The retrieval device 1004 includes an elongatemember 1041 having a distal end that extends interior of the artery, aproximal end that extends exterior of the artery and a plurality ofradical pins 1048, and a plurality of ring elements 1042 arranged at thedistal end 1046 of the elongate member 1041. The ring elements 1042 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements1042 toward the expanded configuration. Each ring element 1042,comprising a plurality of struts 1043, is made of shape memory materialnitinol and each strut features a crown element 1047 with an eyelet1044. The eyelets 1044 engage with the radial pins 1048 to attach thering elements to the elongate member. The radial force is absorbed byradial pins to restrain the ring elements 1042 in the collapsedconfiguration. When microcatheter 1004 is retracted the ring elements1042 are able to expand and disengage eyelets 1044 from pins 1048 andare thus freed to expand towards the fully expanded configuration. Thering elements 1042 engage or capture the clot and the device can then beretracted proximally and removed from the artery. In one embodiment thering elements are connected to the elongate member 1041 by tetherelements 1045 as shown in FIGS. 16 c and 16 d.

Another preferred embodiment of a mechanical clot retrieval device ofthe present invention is illustrated in FIGS. 17 a-17 d . The retrievaldevice 1520 includes an elongate member 1521 having a distal end thatextends interior of the artery, a proximal end that extends exterior ofthe artery, an outer tube 1530 with a plurality of slots 1532 and aretractable inner core wire 1531 which has a proximal end that extendsexterior of the artery, and a plurality of ring elements 1522 configuredat the distal end of the elongate member 1521. The ring elements 1522are self-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements1522 toward the expanded configuration. Each ring element 1522comprising a plurality of struts 1523 is made of shape memory materialnitinol and is interconnected by ring connecting tethers 1525. Eachstrut 1523 has a crown element 1527 with an eyelet 1524. A tether isadvanced out of the slot 1532 to loop 1528 through the eyelet 1524 andadvanced back in the slot 1532 to loop 1526 around the core wire 1531 toengage each ring element 1522 to the elongate member 1521 in atether-loop mechanism. The radial force is absorbed by the tether-loopmechanism to restrain the retrieval device 1520 in the collapsedconfiguration when advancing through a microcatheter (not shown). Thecore wire 1531 is retracted proximally thus disengaging and allowingeach ring element 1522 reach the expanded configuration.

FIGS. 18 a-18 c depict a mechanical clot retrieval device 1540 of thepresent invention which is a variant of the retrieval device 1520 asillustrated in FIGS. 17 a-17 d . FIG. 18 d is a view of a cross-sectionthrough line 1553 of FIG. 18 b . The retrieval device 1540 includes anelongate member 1541 having a distal end that extends interior of theartery, a proximal end that extends exterior of the artery, an outertube 1550 with a plurality of slots 1552 and a retractable inner corewire 1551 having proximal end 1549 that extends exterior of the artery,and a plurality of ring elements 1542 arranged at the distal end of theelongate member 1541. The ring elements 1542 are self-expandable from acollapsed configuration to an expanded configuration and have a radialforce that biases the ring elements 1542 toward the expandedconfiguration. Each ring element 1542, comprising a plurality of struts1543, is made of shape memory material nitinol and is interconnected byring connecting tethers (not shown). Each strut 1543 has a crown element1547 with an eyelet 1544. The core wire 1551 is advanced out of eachslot 1552 to loop 1546 through each eyelet 1544 and advanced back in theslot 1552 to loop inside the outer tube 1550 to engage each ring element1542 to the elongate member 1541 in a tether-loop mechanism. The radialforce is absorbed by the tether-loop mechanism to restrain the retrievaldevice 1540 in the collapsed configuration when advancing through amicrocatheter (not shown). The core wire 1551 is retracted in order todisengage and allow each ring element 1542 reach the expandedconfiguration.

FIGS. 19 a-19 d represents a mechanical clot retrieval device of thepresent invention which is yet another slightly variant embodiment ofthe retrieval device 1520 as illustrated in FIGS. 17 a-17 d . Theretrieval device 1560 includes an elongate member 1561 having a distalend 1569 that extends interior of the artery, a proximal end thatextends exterior of the artery and a tube lumen 1570 with a plurality ofslots 1571, and a plurality of ring elements 1562 configured at thedistal end of the elongate member 1561. The ring elements 1562 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements1562 toward the expanded configuration. Each ring element 1562,comprising a plurality of struts 1563, is made of shape memory materialnitinol and is interconnected by ring connecting tethers 1565. Eachstrut 1563 has a crown element 1568 with an eyelet 1564. A plurality oftethers 1566 is positioned within the lumen 1570 and is advanced out ofeach slot 1571 to loop 1567 each eyelet 1564 and is attached at a distalend 1569 of the elongate member 1561 to engage each ring element 1562 tothe elongate member 1561 in a tether-loop mechanism. The radial force isabsorbed by the tether-loop mechanism to restrain the retrieval device1560 in the collapsed configuration when advancing through amicrocatheter (not shown). The tethers 1566 are broken or cut todisengage and allow each ring element 1562 reach an expandedconfiguration.

FIGS. 20 a-20 b shows a mechanical clot retrieval device 1580 of thepresent invention. The retrieval device 1580 includes an elongate member1581, a distal end 1569 that extends interior of the artery and aproximal end that extends exterior of the artery, a plurality of ringelements 1582 configured at the distal end of the elongate member 1581and a proximal collar 1589 attached to an abutment tube 1588. The ringelements 1582 are self-expandable from a collapsed configuration to anexpanded configuration and feature a radial force that biases the ringelements 1582 toward the expanded configuration. Each ring element 1582,comprising a plurality of struts 1583, is made of shape memory materialnitinol and is attached to the elongate member 1581 by connectingtethers 1585. Each strut 1583 has a crown element 1587. A tether iswrapped around each ring element 1582 and is attached to the elongatemember 1581 by a tether loop 1584 to engage each ring element 1582 tothe elongate member 1581 in a tether-loop mechanism. The radial force isabsorbed by the tether-loop mechanism to restrain the retrieval device1580 in the collapsed configuration when it is advancing through amicrocatheter (not shown). The elongate member 1581 is retractedproximally thus sliding the tether loop 1584 off the ring element 1582and disengaging and therefore allowing each ring element 1582 reach theexpanded configuration.

Another preferred embodiment of a mechanical clot retrieval device ofthe present invention is illustrated in FIGS. 21 a-21 f . The retrievaldevice 2020 includes an elongate member 2021 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 2022 configured at thedistal end of the elongate member 2021, and a plurality of beveled 2029or recessed 2028 collars 2026 configured at distal and proximal ends ofeach ring element 2022. The ring elements 2022 are self-expandable froma collapsed configuration to an expanded configuration and comprise aradial force that biases the ring elements 2022 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by collars 2026. Each ring element 2022, comprising a pluralityof struts 2023, is made of shape memory material nitinol and isinterconnected by tethers (not labeled) and attached to the elongatemember 2021 by ring connecting tethers 2025. Each strut 2023 includes acrown element 2027 with a tab 2024 extending axially and radially inwardand may be bevel or square shape in shape. The tab 2024 engages with thecollar 2026 to restrain the ring element 2022 to the elongate member2021 in a collar mechanism. The collar mechanism restrains the retrievaldevice 2020 in the collapsed configuration when advancing through amicrocatheter (not shown). The elongate member 2021 is retractedproximally to disengage it and allow each ring element 2022 reach theexpanded configuration.

FIGS. 22 a-22 d shows a method for using the device 2020 in accordancewith the preferred embodiment shown in FIGS. 21 a-21 f A guidewire (notshown) is inserted in a cerebral artery 2000 and is advanced across anobstructive clot 2001. An intravascular microcatheter 2003 is advancedover the guidewire to a location proximal to the clot 2001 and then amechanical clot retrieval device 2020, sheathed within a bumper tube2030, is advanced through the microcatheter 2003 to the clot 2001 in acollapsed configuration. The microcatheter 2003 is retracted when theretrieval device 2020 is located distal of the clot. It is unsheathed toallow ring elements 2022 to reach the expanded configuration. Theelongate member 2021 of the retrieval device 2020 allows the physicianto manually disengage the collar mechanism and the ring connectingtether 2025 attached to the elongate member 2021. The ring elements 2022engage or capture the clot 2001 from the distal surface of the clot 2001and retract the clot 2001 proximally to the microcatheter 2003.

FIGS. 23 a-23 c depicts a mechanism used in a mechanical clot retrievaldevice 2040 for engaging a tab 2044 with a collar 2046 in a slightvariant with the preferred embodiment shown in FIGS. 21 a-21 f . Theretrieval device 2040 includes an elongate member 2041 having a distalend that extends interior of the artery and a proximal end that extendsexterior of the artery, a ring element 2042 configured at the distal endof the elongate member 2041 and a proximal collar 2046. The ring element2042 is self-expandable from a collapsed configuration to an extendedconfiguration and has a radial force that biases the ring element 2042toward the expanded configuration. In the collapsed configuration, theradial force is absorbed by the proximal collar 2046. The ring element2042, comprising plurality of struts 2043, is made of shape memorymaterial nitinol and each strut 2043 has a crown element 2047 with a tab2044 extending axially and radially inward. The tab 2044 is shaped toengage with the collar 2046, having a recess to restrain the ringelement 2042 to the elongate member 2041 in a collar mechanism. Thecollar mechanism restrains the retrieval device 2040 in the collapsedconfiguration when advancing through a microcatheter (not shown). Theelongate member 2041 is retracted proximally to disengage it and alloweach ring element 2042 reach the expanded configuration.

FIGS. 24 a-24 c shows a mechanical clot retrieval device 2060 of thepresent invention which is a slightly variant embodiment of theretrieval device 2020 as illustrated in FIGS. 21 a-21 f The retrievaldevice 2060 includes an elongate member 2061 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 2062 configured at thedistal end of the elongate member 2061, and a plurality of collars 2066having a plurality of holes 2068 configured proximally of each ringelement 2062. The ring members 2062 are self-expandable from a collapsedconfiguration to an expanded configuration and comprise a radial forcethat biases the ring elements 2062 toward the expanded configuration. Inthe collapsed configuration, the radial force is absorbed by collars2066. Each ring element 2062, comprising a plurality of struts 2063, ismade of shape memory material nitinol and is interconnected by ringconnecting tethers 2069. Each strut 2063 has a crown element 2067 with apin 2064 extending axially and radially inward. The pin 2064 engageswith the hole 2068 to restrain the ring elements 2062 to the elongatemember 2061 in a collar mechanism. The device includes a pair of cables2065 having distal ends which are attached to the most proximal ringelement 2062 and proximal ends that extend exterior of the artery formanipulation and control by the physician. The collar mechanismrestrains the retrieval device 2060 in the collapsed configuration whenit is advancing through a microcatheter 2003. The cables 2065 aremanually pulled proximally to disengage the collar mechanism and alloweach ring element 2062 reach the expanded configuration.

FIGS. 25 a-25 k represents a mechanical clot retrieval device 2080 ofthe present invention which is another slightly variant embodiment ofthe retrieval device 2020 as illustrated in FIGS. 21 a-21 f . Theretrieval device 2080 includes elongate member 2081 a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 2082 configured at thedistal end of the elongate member 2081, and a plurality of shapedengagement collars 2085 having a plurality of dove tail grooves 2088configured proximally of each ring element 2082. The ring elements 2082are self-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements2082 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by collars 2085. Each ring element 2082,comprising a plurality of struts 2083, is made of shape memory materialnitinol and is attached to the elongate member 2081 by tethers 2089.Each strut 2083 has a crown element 2087 with a shaped tab 2084extending axially and radially inward. The shaped tab 2084 engages withthe shaped engagement collar 2085 to restrain the ring element 2082 tothe elongate member 2081 in a collar mechanism. The collar mechanismrestrains the retrieval device 2080 in the collapsed configuration whenit is advancing through a microcatheter (not shown). The elongate member2081 is manually retracted proximally to disengage it and allow eachring element 2082 reach the expanded configuration.

FIGS. 26 a-26 c represents a slightly variant embodiment of theretrieval device 2080 as represented in FIGS. 25 a-25 k , havingadditional ring connecting tethers 2101 interconnecting each ringelement 2082.

Another preferred embodiment of a mechanical clot retrieval device 2520of the present invention is illustrated in FIGS. 27 a-27 b . Theretrieval device 2520 includes an elongate member 2521 having a distalend that extends interior of the artery, a proximal end that endsinterior of the artery and an inner lumen 2529 with a plurality ofopenings (not labeled), and a plurality of ring elements 2522 configuredat the distal end of the elongate member 2521. The ring elements 2522are self-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases ring elements 2522toward the expanded configuration. Each ring element 2522, comprising aplurality of struts 2523, is interconnected by ring connecting tethers2525. Each strut 2523 has a crown element 2527 and an engagement tab2524. A plurality of tether loops 2526 having proximal ends that extendexterior of the lumen 2529 is advanced out of each opening (not opening)to circle the engagement tab 2524 and engage each ring element 2522 tothe elongate member 2521 in an eyelet mechanism. The radial force isabsorbed by the eyelet mechanism to restrain the retrieval device 2520in the collapsed configuration when it is advancing through amicrocatheter (not shown). The tethers are manually pulled proximally todisengage them and allow each ring element 2522 to reach the expandedconfiguration.

FIGS. 28 a-28 b represents a mechanical clot retrieval device 2540 ofthe present invention which is a slightly variant embodiment of theretrieval device 2520 as illustrated in FIGS. 27 a-27 b . The retrievaldevice 2540 includes an elongate member 2541 having a distal end thatextends interior of the artery, a proximal end that extends exterior ofthe artery and a plurality of raised tabs 2548, and a plurality of ringelements 2542 configured at the distal end of the elongate member 2541.The ring elements 2542 are self-expandable from a collapsedconfiguration to an expanded configuration and comprise a radial forcethat biases the ring elements 2542 toward the expanded configuration. Inthe collapsed configuration, the radial force is absorbed by raised tabs2548. Each ring element 2542, comprising a plurality of struts 2543, isinterconnected by ring connecting tethers 2545. Each strut 2543 has acrown element and an engagement tab 2544. The engagement tab 2544engages with the raised tab 2548 to restrain the ring element 2542 tothe elongate member 2541 in an eyelet mechanism. The eyelet mechanismrestrains the retrieval device 2540 in the collapsed configuration whenit is advancing through a microcatheter (not shown). The elongate member2541 is manually retracted proximally to disengage it and allow eachring element 2542 to reach the expanded configuration.

FIGS. 29 a-29 h shows a method for using a mechanical clot retrievaldevice 2560 in accordance with the preferred embodiment shown in FIGS.27 a-27 b and 28 a-28 b . A guidewire 2502 is inserted in a cerebralartery 2500 and is advanced through an obstructive clot 2501. Anintravascular microcatheter 2503 is advanced over the guidewire 2502 toa location distal to the clot 2501 and then the retrieval device 2560 isadvanced through the microcatheter 2503 to the clot 2501 in a collapsedconfiguration. The microcatheter 2503 is retracted when the retrievaldevice 2560 is positioned distal of the clot 2501 to allow a pluralityof ring elements 2562 to reach an expanded configuration. The ringelements 2562, comprising a plurality of struts 2563, are interconnectedby ring connecting tethers 2565. A tether 2564 is attached at a distalend of the retrieval device 2560 and its proximal end extends out of theartery. The elongate member 2561 and tether 2564 allows the physician tomanually disengage eyelet mechanism. The ring elements 2562 engage orcapture the clot 2501 from the distal end of the clot 2501 and retractthe clot 2501 proximally to the microcatheter 2504.

Another embodiment of a mechanical clot retrieval device 3020 of thepresent invention is illustrated in FIGS. 30 a-30 e . The retrievaldevice 3020 includes an elongate member 3021 designed to have a distalend that extends interior of the artery, a proximal end that extendsexterior of the artery, a plurality of engagement diameters 3028 and aplurality of disengagement diameters 3029, a plurality of ring elements3022 configured at the distal end of the elongate member 3021, and aproximal abutment tube 3031. The ring elements 3022 are self-expandablefrom a collapsed configuration to an expanded configuration and comprisea radial force that biases the ring elements 3022 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the engagement diameters. Each ring element 3022 comprisinga plurality of struts 3023 is interconnected by ring connecting tethers3025. Each strut 3023 has a crown element 3027 with a C-shapedengagement tab 3030 extending radially inward. The C-shaped engagementtab 3030 engages with the engagement diameter 3028 to restrain the ringelement 3022 to the elongate member 3021 in the collapsed configurationwhen it is advanced through a microcatheter (not shown). The devicefeatures a pair of control tethers 3026 having distal ends which areattached to the crown element 3027 of the most proximal ring element3022. The axial movement of the elongate member 3021 disengages eachring element 3022 at the disengagement diameter 3029 and allows eachring element 3022 to reach the expanded configuration.

FIGS. 31 a-31 e shows a mechanical clot retrieval device 3040 of thepresent invention which is a slightly variant embodiment of theretrieval device 3020 as illustrated in FIGS. 30 a-30 e . The retrievaldevice 3040 includes an elongate member 3041 having a distal end thatextends interior of the artery, a proximal end that extends exterior ofthe artery and an inner wire 3051, a plurality of ring elements 3042arranged at a distal end of the elongate member 3041, and a proximalabutment tube 3052. The ring elements 3042 are self-expandable from acollapsed configuration to an expanded configuration and comprise aradial force that biases the ring elements 3042 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the elongate member having inner wire 3051. Each ringelement 3042 comprising a plurality of struts 3042 is interconnected byring connecting tethers 3045. Each strut 3043 has a crown element 3047with a C-shaped engagement tab 3050 extending radially inward. TheC-shaped engagement tab 3050 engages with the elongate member 3041. Theinner wire 3051 restrains the retrieval device 3040 in the collapsedconfiguration when it is advanced through a microcatheter (not shown).The device features a pair of control tethers 3046 having distal endswhich are attached to the crown element 3047 of the most proximal ringelement 3042 and proximal ends which are attached to the abutment tube3052. The withdrawal of the inner wire 3051 disengages it and allowseach ring element 3042 reach the expanded configuration.

FIGS. 32 a-32 d illustrates the mechanical clot retrieval device 3060 ofthe present invention. The retrieval device 3060 includes an elongatemember 3061 having a distal end that extends interior of the artery, aproximal end that extends exterior of the artery and an inner lumen 3071with a plurality of slots 3070, a plurality of ring elements 3062configured at the distal end of the elongate member 3061, and a proximalcollar 3066. The ring elements 3062 are self-expandable from a collapsedconfiguration to an expanded configuration and comprise a radial forcethat biases the ring elements 3062 toward the expanded configuration. Inthe collapsed configuration, the radial force is absorbed by slots 3070.Each ring element 3062, comprising a plurality of struts 3063, isinterconnected by ring connecting tethers 3065. Each strut 3063 has acrown element 3067 with a stepped engagement tab 3064 extendinglongitudinally and radially. The engagement tab 3064 engages with theslot 3070 to restrain the ring elements 3062 to the elongate member 3061and to restrain the retrieval device 3060 in the collapsed configurationwhen it is advanced through a microcatheter (not shown). A pair ofcontrol tethers 3068 is attached from the crown element 3067 of the mostproximal ring element 3062, to the proximal collar 3066. The proximalcollar 3066 is manually pulled proximally to disengage it and allow thering elements 3062 to reach an expanded configuration.

FIGS. 33 a-33 g represents another embodiment of a mechanical clotretrieval device of the present invention. The retrieval device 3080includes an elongate member 3081 having a distal end that extendsinterior of the artery, a proximal end that extends exterior of theartery and a plurality of monofilaments 3088, a plurality of ringelements 3082 configured at the distal end of the elongate member 3081,and a proximal collar 3086. The ring elements 3082 are self-expandablefrom a collapsed configuration to an expanded configuration and comprisea radial force biasing the ring elements 3082 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the monofilaments. Each ring element 3082 comprising aplurality of struts 3083 is interconnected by ring connecting tethers3085. Each strut 3082 has a crown element 3087 with a C-shapedengagement tab 3084. The C-shaped engagement tab 3084 engages with themonofilament 3088 to restrain the ring element 3082 to the elongatemember 3081 in a snap-fit mechanism. The snap-fit mechanism restrainsthe retrieval device 3080 in the collapsed configuration when it isadvancing through a microcatheter (not shown). The device contains apair of control tethers 3089 having distal ends which are attached tothe crown element 3087 of the most proximal ring element 3082 andproximal ends which are attached to the collar 3086. The elongate member3081 is manually retracted to disengage it and allow each ring element3082 reach the expanded configuration.

Another embodiment of a mechanical clot retrieval device of the presentinvention is shown in FIGS. 34 a-34 j . The retrieval device 3100includes an elongate member 3101 having a distal end that extendsinterior of the artery, a proximal end that extends exterior of theartery and a plurality of inactivated cuffs 3108 a configured at thedistal end of the elongate member 3101, a plurality of ring elements3102 configured over the cuff 3108 a, and a tube 3106. Each cuff 3108 ais made of electro-active polymer which swells to an activated state3108 b when current is applied. The ring elements 3102 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force biasing the ring elements 3102toward the expanded configuration. Each ring element 3102 comprising aplurality of struts 3103 is interconnected by ring connecting tethers3105. Each strut has a crown element 3107. A pair of control tethers3104 are attached to the crown element 3107 of the most proximal ringelement 3102, having proximal ends that extend out of the artery. A ringrestraining tether 3109 is wrapped around each ring element 3102restraining it to the elongate member 3101 in the collapsedconfiguration when it is advanced through a microcatheter (not shown).In the collapsed configuration, the radial force is absorbed by the ringrestraining tethers 3109. The current is applied through the restrainingtether 3109 to allow each cuff 3108 a to reach activated state 3108 band then they are manually pulled proximally to disengage them and alloweach ring element 3102 reach the expanded configuration.

FIGS. 35 a-35 b represents another embodiment of a mechanical clotretrieval device of the present invention. The retrieval device 3120includes an elongate member 3121 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a plurality of ring elements 3122 configured at the distal endof the elongate member 3121, a proximal collar 3129, and a bumper tube3126. The ring elements 3122 are self-expandable from a collapsedconfiguration to an expanded configuration and have a radial forcebiasing the ring elements 3122 toward the expanded configuration. Eachring element 3122, comprising a plurality of struts 3123, isinterconnected by ring connecting tethers 3125. Each strut 3123 has acrown element 3127 with an eyelet 3128. A tether loop 3130 engages eachring element 3122 to the elongate member 3121 to restrain the retrievaldevice 3120 in the collapsed configuration when it is advancing througha microcatheter 3003. In the collapsed configuration, the radial forceis absorbed by tether loops 3130. The device contains a pair of controltethers 3124, having distal ends which are attached to the crown element3127 of the most proximal ring element 3122 and proximal ends whichextend out of the artery. The elongate member 3121 is manually retractedproximally to disengage it and allow each ring element 3122 reach theexpanded configuration.

Another embodiment of a mechanical clot retrieval device of the presentinvention is shown in FIGS. 36 a-36 d . The retrieval device 3140includes an elongate member 3141 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a plurality of ring elements 3142 arranged at the distal end ofthe elongate member 3141, a bumper tube 3146 and a proximal collar 3149.The ring elements 3142 are self-expandable from a collapsedconfiguration to an expanded configuration and comprise a radial forcebiasing ring elements toward the expanded configuration. In thecollapsed configuration, the radial force is absorbed by the elongatemember 3141. Each ring element 3142 comprising a plurality of struts3143 is interconnected by ring connecting tethers 3145. Each strut 3143has a crown element 3147 with an engagement tab 3148 having an eyelet3144. The elongate member 3141 passes through each eyelet 3144 engagingeach ring element 3142 to the elongate member 3141 to restrain theretrieval device 3140 in the collapsed configuration when it isadvancing through a microcatheter 3003. The elongate member 3141 ismanually retracted proximally to disengage it and allow each ringelement 3142 reach the expanded configuration.

FIGS. 37 a-37 i represents a mechanical clot retrieval device of thepresent invention which is a slightly variant embodiment of theretrieval device 3140 as shown in FIGS. 36 a-36 d . The retrieval device3160 includes an elongate member 3161 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a plurality of ring elements 3162 configured at the distal endof the elongate member 3161, a bumper tube (not labeled) and a proximalcollar (not labeled). The ring elements 3162 are self-expandable from acollapsed configuration to an expanded configuration and comprise aradial force biasing the ring elements 3162 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the elongate member 3161. Each ring element 3162 comprisinga plurality of struts 3163 is interconnected by ring connecting tethers(not labeled). Each strut has a crown element 3167 with an engagementtab 3166 and an eyelet 3168. The elongate member 3161 passes througheach eyelet 3168 engaging each ring element 3162 to the elongate member3161 to restrain the retrieval device 3160 in the collapsedconfiguration when it is advancing through a microcatheter 3003. Theelongate member 3161 is manually retracted proximally to disengage andallow each ring element 3162 reach the expanded configuration.

Another embodiment of a mechanical clot retrieval device of the presentinvention is illustrated in FIGS. 38 a-38 d . The retrieval device 3200has an elongate member 3201 having a distal end that extends interior ofthe artery, a proximal end that extends exterior of the artery and aplurality of restraining loops 3206 configured at the distal end of theelongate member 3201, and a plurality of ring elements 3202 arranged atthe distal end of the elongate member 3201. The ring elements 3202 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements3202 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by the restraining loops 3206. Each ringelement 3202 comprising a plurality of struts 3203 is connected to theloop 3206 by connecting tethers 3205. Each strut 3203 is having a crownelement 3207. The device features a pair of control tethers 3204, havingdistal ends which are attached to the crown element 3207 of the mostproximal ring element 3202, and proximal ends that extend out of theartery. The loops 3206 engage the ring elements 3202 to the elongatemember 3201 in an offset loop mechanism. The offset loop mechanismrestrains the retrieval device 3200 in the collapsed configuration whenit is advanced through a microcatheter (not shown). The elongate member3201 is manually retracted proximally to disengage it and allow eachring element 3202 to reach the expanded configuration.

Another embodiment of a mechanical clot retrieval device 3300 of thepresent invention is illustrated in FIGS. 39 a-39 d . The retrievaldevice 3300 has an elongate member 3301 having a distal end that extendsinterior of the artery and a proximal end that extend exterior of theartery, a plurality of ring elements 3302 arranged at the distal end ofthe elongate member 3301, a bumper tube 3306, and a proximal collar3308. The ring elements 3302 are self-expandable from a collapsedconfiguration to an expanded configuration and comprise a radial forcethat biases the ring elements toward the expanded configuration. In thecollapsed configuration, the radial force is absorbed by the elongatemember 3301. Each ring element 3302, comprising a plurality of struts3303, is interconnected by ring connecting tethers 3305. Each strut 3303has a crown element 3307. The device has comprises a pair of controltethers 3304, having distal ends which are attached to the crown element3307 of the most proximal ring element 3302 and proximal ends that areattached to the bumper tube 3306. The crown element 3307 of each strut3303 is confined around the elongate member 3301 to restrain the ringelement 3302 to the elongate member 3301 when it is advanced through amicrocatheter 3309. The elongate member 3301 is retracted proximally todisengage it and allow each ring element 3302 to reach the expandedconfiguration.

FIGS. 40 a-40 e and 41 a-41 d shows a method of advancing a mechanicalclot retrieval device 3405 in accordance with a preferred embodiment ofthe present invention in a tortuous vessel 3400. A guidewire 3402 isinserted in the vessel 3400 and is advanced through an obstructive clot3401. An intravascular microcatheter 3403 is advanced over the guidewireto a location distal to the clot 3401 and then the retrieval device 3405is advanced through the microcatheter 3403 to the clot 3401 in acollapsed configuration. The microcatheter 3403 is retracted to allowthe plurality of ring elements (not labeled) to reach an expandedconfiguration. The ring elements (not labeled) contain a plurality ofstruts (not labeled). Each ring element is connected to the next ringelement (not labeled) by a ring connecting tether 3406. A control tether3407 is attached to the strut (not labeled) of the proximal ring elementhaving a proximal end that extends out of the patient to allow physicianto manually maneuver the retrieval device 3405. The retrieval device3405 engages or captures the clot 3401 from the distal end of the clot3401 and retracts the clot 3401 proximally into the microcatheter 3403.

FIGS. 42 a-42 d, 43 a-43 h and 44 a-44 b illustrates the mechanical clotretrieval device 3420 of the present invention. The retrieval device3420 includes an elongate member 3421 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, and a plurality of ring elements 3422 configured at the distalend of the elongate member 3421. The ring elements 3422 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements3422 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by an intravascular microcatheter (notshown) through which the retrieval device 3420 is delivered inside theartery. Each ring element 3422, comprising a plurality of struts 3423,is interconnected by ring connecting tethers 3425. Each strut 3423 has acrown element 3427 with or without a shaped tab 3428 or an eyelet 3426.The crown element 3427 is connected to neighboring crown element 3427 bythe tether 3425 which may be looped around tab 3428 or passed througheyelet 3426.

The crown element 3427 which is without the shaped tab 3428 or theeyelet 3426 may be connected to neighboring crown element 3427 by anadhesive bond 3429. Crown-to-crown 3427 connection restrains theretrieval device 3420 in the collapsed configuration when advancedthrough the intravascular microcatheter (not shown). The device featuresa pair of removal tethers 3424, having distal ends which are attached tothe crown element 3427 of the most proximal ring element 3422, andproximal ends that extend out of the artery. The microcatheter isretracted proximally and tether 3424 is manually pulled proximally todisengage it and allow each ring element 3422 reach the expandedconfiguration.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 45 . The retrieval device 3440 has anelongate member 3441 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3442 having a first diameter and a seconddiameter, and a control strut 3444 having distal end attached toproximal ring element 3442 and proximal end attached to the elongatemember 3441 by adhesive bonds 3446. The ring elements 3442 areself-expandable from a collapsed configuration to an expandedconfiguration and have a radial force that biases the ring elements 3442toward the expanded configuration. In the collapsed configuration, theradial force is absorbed by an intravascular microcatheter (not shown)through which the retrieval device 3440 is delivered inside the artery.Each ring element 3442, comprising a plurality of struts 3443, isconnected by ring connecting tethers 3445. Each strut 3443 has a crownelement 3447. The crown element 3447 is connected to neighboring crownelement 3447 by the tether 3445. Crown-to-crown connection restrains theretrieval device 3440 in the collapsed configuration when it is advancedthrough the microcatheter (not shown). The microcatheter is retractedproximally and each ring element 3442 disengages to create a zigzagstent surface for improved clot engagement.

FIG. 46 represents a mechanical clot retrieval device 3460 of thepresent invention which is a slightly variant embodiment of theretrieval device as illustrated by FIG. 46 . The retrieval device 3460has an elongate member 3461 having a distal end that extends interior ofthe artery and a proximal end that extends exterior of the artery, aplurality of ring elements 3462 attached at the distal end of theelongate member and a control strut 3464 having a distal end attached tothe most proximal ring element 3462 and a proximal end attached to theelongate member 3461 by adhesive bonds 3466. The ring elements 3462 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elementstoward the expanded configuration. In the collapsed configuration, theradial force is absorbed by an intravascular microcatheter (not shown)through which the retrieval device 3460 is delivered inside the artery.Each ring element 3462, comprising a plurality of struts 3463, isconnected by ring connecting tethers 3465. Each strut 3463 has a crownelement 3467. The crown element 3467 is connected to the neighboringcrown 3467 by a connecting strut 3468 to restrain the retrieval device3460 in the collapsed configuration when it is advanced through themicrocatheter (not shown). The microcatheter is retracted proximally andeach ring element 3462 disengages to create a zigzag stent surface forimproved clot engagement.

FIG. 47 represents a mechanical clot retrieval device 3480 of thepresent invention which is another variant embodiment of the retrievaldevice as illustrated in FIG. 46 . The retrieval device 3480 has anelongate member 3481 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3482 and a control strut 3484 having a distalend attached to the proximal ring element 3482 and a proximal endattached to the elongate member 3481. The ring elements 3482 areself-expandable from a collapsed configuration to an expandedconfiguration and have a radial force that biases the ring elements 3482toward the expanded configuration. In the collapsed configuration, theradial force is absorbed by an intravascular microcatheter, throughwhich the retrieval device 3480 is delivered inside the artery. Eachring element 3482, comprising a plurality of struts 3483, is connectedby ring connecting tethers 3485. Each strut 3483 has a crown element3487. The crown element 3487 is connected to the neighboring crown 3487by the tether 3485 and adhesive bond 3486. Crown-to-crown connectionrestrains the retrieval device 3480 in the collapsed configuration whenit is advanced through a microcatheter (not shown). The microcatheter isretracted and each ring element 3482 disengages to create a zigzag stentsurface for improved clot engagement.

Another preferred embodiment of a mechanical clot retrieval device ofthe present invention is illustrated in FIGS. 48 a-48 f . The retrievaldevice 3500 includes an elongate member 3501 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 3502, and a pair of removaltethers 3504 having distal ends attached to the proximal ring element3502 and proximal ends attached to the elongate member 3501. The ringelements 3502 are self-expandable from a collapsed configuration to anexpanded configuration and have a radial force that biases the ringelements 3502 toward the expanded configuration. In the collapsedconfiguration, the radial force is absorbed by an intravascularmicrocatheter 3403, through which the retrieval device 3500 is deliveredinside the artery. Each ring element 3502, comprising a plurality ofstruts 3503, is interconnected by ring connecting tethers 3505. Eachstrut 3503 has a crown element 3507. The distally facing crown element3507 is connected to the neighboring proximally facing crown 3507 by thetether 3505. Crown-to-crown connection restrains the retrieval device3500 in the collapsed configuration when advanced through themicrocatheter 3403. The microcatheter 3403 is advanced inside atorturous artery 3400 and is positioned distal of an obstructive clot3401. The microcatheter 3403 is retracted to allow each ring element3502 reach the expanded configuration and engage or capture the clot3401 from the distal end of the clot 3401 and the device is thenretracted proximally into the microcatheter 3403.

FIGS. 49 a-49 f represents a mechanical clot retrieval device of thepresent invention which is a slightly variant embodiment of theretrieval device 3500 as illustrated in FIGS. 48 a-48 f The retrievaldevice has an elongate member 3521 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a plurality of ring elements 3522, and a control strut 3524having a distal end attached to the proximal ring element 3522 and aproximal end attached to the elongate member 3521. The ring elements3522 are self-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements3522 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by an intravascular microcatheter 3403through which the retrieval device 3520 is delivered inside the artery.Each ring element 3522, comprising a plurality of struts 3523, isconnected by ring connecting tethers 3525. Each strut 3523 has a crownelement 3527. The distally facing crown element 3527 is connected toneighboring proximally facing crown 3527 by the tether 3525.Crown-to-crown 3527 connection restrains the retrieval device 3520 inthe collapsed configuration when advanced through the microcatheter3403. The microcatheter 3403 is advanced over a guidewire (not shown)inside a torturous artery 3400 and positioned distal of an obstructiveclot 3401. The microcatheter 3403 is retracted proximally to allow eachring element 3522 reach the expanded configuration and engage or capturethe clot 3401 from the distal end of the clot 3401 and the device isthen retracted proximally into the microcatheter 3403.

FIGS. 50 a-50 g shows a mechanical clot retrieval device 3540 a of thepresent invention which is another slightly variant embodiment of theretrieval device 3500 as illustrated in FIGS. 48 a-48 f . The retrievaldevice 3540 a includes an elongate member 3541 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 3542 configured at thedistal end of the elongate member 3541 and a plurality of connectingtethers 3545 having distal ends attached to the ring element 3542 andproximal ends attached to the elongate member 3541. The ring elements3542 are self-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements3542 toward the expanded configuration. In the collapsed configuration,the radial force is absorbed by an intravascular microcatheter 3403through which the retrieval device 3540 a is delivered inside theartery. Each ring element 3542 comprising a plurality of struts 3543.Each strut 3543 has a crown element 3547. The distally facing crownelement 3547 is connected to neighboring proximally facing crown 3547 bythe tether 3545. Crown-crown 3547 connection restrains the retrievaldevice 3540 a in the collapse configuration when advanced through amicrocatheter 3403. The microcatheter 3403 is advanced over a guidewire(not shown) inside a tortuous artery 3400 and positioned distal of anobstructive clot 3401. The microcatheter 3403 is retracted to allow eachring element 3542 to reach the expanded configuration and engage orcapture the clot 3401 from the distal base of the clot 3401 and thedevice is then retracted proximally to the microcatheter 3403.

Another embodiment of a mechanical clot retrieval device 3560 of thepresent invention is illustrated in FIGS. 51 a-51 f . The retrievaldevice 3560 includes an elongate member 3561 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a plurality of ring elements 3562 configured at thedistal end of the elongate member 3561, a plurality of connectingtethers 3565 having distal ends attached to the ring element 3562 andproximal ends attached to the elongate member 3561, and a pair ofremoval tethers 3564 having distal ends attached to the most proximalring element 3562 and proximal ends that extend out of the artery. Thering elements 3562 are self-expandable from a collapsed configuration toan expanded configuration and comprise a radial force that biases thering elements 3562 toward the expanded configuration. In the collapsedconfiguration, the radial force is absorbed by an intravascularmicrocatheter 3403 through which the retrieval device 3560 is deliveredinside the artery. Each ring element 3562 comprises a plurality ofstruts 3563. Each strut 3563 has a crown element 3567. The connectingtether 3565 engages each ring element 3562 to the elongate member 3562to restrain the retrieval device 3560 in the collapsed configurationwhen it is advanced through a microcatheter 3403. The microcatheter 3403is advanced over a guidewire (not shown) inside a tortuous artery 3400and positioned distal of an obstructive clot 3401. The microcatheter3403 is retracted to allow each ring element 3562 reach the expandedconfiguration and engage or capture the clot 3401 from the distal baseof the clot 3401 and retracted proximally to the microcatheter 3403.

FIGS. 52 a-52 d represents a mechanical clot retrieval device 3580 ofthe present invention which is a slightly variant embodiment of theretrieval device 3560 as illustrated in FIGS. 51 a-51 f . The retrievaldevice 3580 has an elongate member 3581 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a plurality of ring elements 3582 configured at the distal endof the elongate member 3581 and a plurality of connecting tethers 3585having distal ends attached to the ring member 3582 and proximal endsattached to the elongate member 3581. The ring elements 3582 areself-expandable from a collapsed configuration to an expandedconfiguration and comprise a radial force that biases the ring elements3582 towards the expanded configuration. In the collapsed configuration,the radial force is absorbed by an intravascular microcatheter 3403through which the retrieval device 3580 is delivered inside the artery.Each ring element 3582 comprises a plurality of struts 3583. Each strut3583 has a crown element 3587. Each ring element 3582 is wrapped aroundthe elongate member 3581 to restrain the retrieval device 3580 in thecollapsed configuration when it is advanced through a microcatheter3403. The microcatheter 3403 is advanced over a guidewire (not shown)inside a tortuous artery and positioned distal of an obstructive clot3401. The microcatheter 3403 is retracted to allow each ring element3582 to reach the expanded configuration and engage or capture the clot3401 from the distal base of the clot (not shown) and then the device isretracted proximally into the microcatheter 3403.

FIGS. 53 a-53 f shows a method of using a mechanical clot retrievaldevice 3600 of the present invention in the embodiment as illustrated inFIGS. 52 a-52 d . A guide catheter 3601 is inserted inside the arteryand a guidewire (not shown) is advanced within the catheter 3601bypassing an occlusive clot (not shown). A microcatheter 3602 isadvanced over the guidewire (not shown) to a location distal to the clot(not shown) and then the retrieval device 3600 is advanced through themicrocatheter 3602 to the clot (not shown) in a collapsed configuration.The microcatheter 3602 is retracted to allow ring elements 3604 to reachan expanded configuration. The ring elements 3604 are self-expandablefrom the collapsed configuration to the expanded configuration and eachring element comprises plurality of struts 3605. Each strut 3605 has acrown element 3607. The ring elements 3604 are attached to the elongatemember 3603 by connecting tethers 3606 and are wrapped around theelongate member 3603 to restrain the retrieval device 3600 in thecollapsed configuration when it is advanced through the microcatheter3602. The ring elements 3604, when expanded, engage or capture the clot(not shown) from the distal base of the clot (not shown) and retract theclot (not shown) proximally to the microcatheter 3602. The retrievaldevice 3600 returns to the collapsed configuration while retracting intothe guide catheter 3601 and is easily removed from the artery.

FIGS. 54 a-54 h shows another method of using a mechanical clotretrieval device 3620 of the present invention in accordance with theembodiment as illustrated in FIGS. 52 a-52 d . A guidewire 3404 isinserted in a tortuous artery 3400 and advanced through an obstructiveclot 3401. A microcatheter 3403 is advanced over the guidewire 3404 to alocation distal to the clot 3401 and then the retrieval device 3620 isadvanced through the microcatheter 3403 to the clot 3401 in a collapsedconfiguration. The microcatheter 3403 is retracted when the retrievaldevice 3620 is positioned distal of the clot 3401 to allow ring elements3622 to reach an expanded configuration. The ring elements 3622 areself-expandable from the collapsed configuration to the expandedconfiguration and are wrapped around the elongate member 3621 torestrain the retrieval device 3620 in the collapsed configuration whenadvanced through the microcatheter 3403. A removal tether 3624 isattached to the retrieval device 3620. The ring elements 3622, whenexpanded using an activation element 3626, engage or capture the clot3401 from the distal base of the clot 3401 and retract the clot 3401proximally to the microcatheter 3603. The retrieval device 3620 returnsto the collapsed configuration while retracting into a guide catheter3627 and is easily removed from the artery 3400.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 55 . The retrieval device 3700 has anelongate member 3701 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3702 a having a larger diameter and aplurality of ring elements having a smaller diameter 3702 b, and acontrol strut 3704 having distal end attached to proximal ring element3702 a and proximal end attached to the elongate member 3701 by adhesivebonds 3706. The ring elements 3702 a and 3702 b are self-expandable froma collapsed configuration to an expanded configuration and have a radialforce that biases the ring elements 3702 a and 3702 b toward theexpanded configuration. In the collapsed configuration, the radial forceis absorbed by an intravascular microcatheter (not shown) through whichthe retrieval device 3700 is delivered inside the artery. Each ringelement 3702 a, and 3702 b comprises a plurality of struts 3703. Eachstrut 3703 has a crown element 3707. The crown element 3707 is connectedto neighboring crown element 3707 by the ring to ring connection 3705.The ring to ring connection 3705 restrains the retrieval device 3700 inthe collapsed configuration when it is advanced through themicrocatheter (not shown). The microcatheter is retracted proximally andeach ring element 3702 disengages to form the expanded configuration.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 56 . The retrieval device 3720 has anelongate member 3721 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3722, and a removal tether 3724 having distalend attached to proximal ring element 3722 and proximal end attached tothe elongate member 3721. The ring elements 3722 are self-expandablefrom a collapsed configuration to an expanded configuration and have aradial force that biases the ring elements 3722 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by an intravascular microcatheter (not shown) through which theretrieval device 3720 is delivered inside the artery. Each ring element3722 comprises a plurality of struts 3723. The outer mesh 3725 restrainsthe retrieval device 3720 and limits it to a certain diameter in theexpanded configuration. The microcatheter is retracted proximally andeach ring element 3722 disengages to form the maximum allowable diameterwithin the outer mesh.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 57 . The retrieval device 3740 has anelongate member 3741 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3742, and a removal tether 3744 having distalend attached to proximal ring element 3742 and proximal end attached tothe elongate member 3741. The ring elements 3742 are self-expandablefrom a collapsed configuration to an expanded configuration and have aradial force that biases the ring elements 3742 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by an intravascular microcatheter (not shown) through which theretrieval device 3740 is delivered inside the artery. Each ring element3742 comprises a plurality of struts 3743. The tether net cover 3745restrains the retrieval device 3740 and limits it to a certain diameterin the expanded configuration. The microcatheter is retracted proximallyand each ring element 3742 disengages to form the maximum diameterallowed by the tether net cover.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 58 . The retrieval device 3760 has anelongate member 3761 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3762, and a control strut 3764 having distalend attached to proximal ring element 3762 and proximal end attached tothe elongate member 3761 by adhesive bonds 3766. The ring elements 3762are self-expandable from a collapsed configuration to an expandedconfiguration and have a radial force that biases the ring elements 3762toward the expanded configuration. In the collapsed configuration, theradial force is absorbed by an intravascular microcatheter (not shown)through which the retrieval device 3760 is delivered inside the artery.Each ring element 3762 comprises a plurality of struts 3763. Each strut3763 has a crown element 3767. The crown element 3767 is connected toneighboring crown element 3767 by the ring to ring connection 3765. Thering to ring connection 3765 restrains the retrieval device 3760 in thecollapsed configuration when it is advanced through the microcatheter(not shown). The microcatheter is retracted proximally and each ringelement 3762 disengages to form the expanded configuration.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 59 . The retrieval device 3780 has anelongate member 3781 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3782, and a removal tether 3784 having distalend attached to proximal ring element 3782 and proximal end attached tothe elongate member 3781. The ring elements 3782 are self-expandablefrom a collapsed configuration to an expanded configuration and have aradial force that biases the ring elements 3782 toward the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by an intravascular microcatheter (not shown) through which theretrieval device 3780 is delivered inside the artery. Each ring element3782 comprises a plurality of struts 3783. The tether net cover 3785restrains the retrieval device 3780 and limits it to a certain diameterin the expanded configuration. The device also comprises a tapered ringelement at the distal end of the tether net cover 3785. Themicrocatheter is retracted proximally and each ring element 3782disengages to form the maximum diameter allowed by the tether net cover3785.

Another embodiment of a mechanical clot retrieval device of the presentinvention is represented in FIG. 60 . The retrieval device 3800 has anelongate member 3801 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, aplurality of ring elements 3802, and a control strut 3804 having distalend attached to proximal ring element 3802 and proximal end attached tothe elongate member 3801 by adhesive bonds 3806. The ring elements 3802are self-expandable from a collapsed configuration to an expandedconfiguration and have a radial force that biases the ring elements 3802toward the expanded configuration. In the collapsed configuration, theradial force is absorbed by an intravascular microcatheter (not shown)through which the retrieval device 3780 is delivered inside the artery.Each ring element 3802 comprises a plurality of struts 3803. Each strut3803 has a crown element 3807. The crown element 3807 is connected toneighboring crown element 3807 by the ring to ring connection 3805. Thering to ring connection 3805 restrains the retrieval device 3800 in thecollapsed configuration when it is advanced through the microcatheter(not shown). The ring elements are wrapped in an outer mesh/net cover3808 which limits the diameter of the ring elements in the expandedconfiguration. The microcatheter is retracted proximally and each ringelement 3802 disengages to form the expanded configuration with themaximum diameter allowed by the outer mesh/net cover 3808.

Another preferred embodiment of a mechanical clot retrieval device 3820of the present invention is illustrated in FIGS. 61 a-61 c . Theretrieval device 3820 is advanced through a microcatheter 3821 insidethe patient artery and includes an activation tether 3824, having adistal end that extends interior of the artery and a proximal end thatextends exterior of the artery, a distal collar 3827, and a plurality ofring elements 3822 configured to the distal end of the activation tether3824. The ring elements 3822 are self-expandable from a collapsedconfiguration to an expanded configuration and have a radial force thatbiases the ring elements 3822 in the expanded configuration. In thecollapsed configuration, the radial force is absorbed by anintravascular microcatheter 3821 through which the retrieval device 3820is delivered inside the artery. Each ring element 3822, comprising aplurality of struts 3823, is interconnected by bridges 3825. Themicrocatheter 3821 is retracted and the activation tether 3824 ismanually pulled proximally to compress the device and allow ringelements 3822 to reach the expanded configuration.

FIGS. 62 a-62 b shows a mechanical clot retrieval device 3840 of thepresent invention which is a slightly variant embodiment of theretrieval device as illustrated in FIGS. 61 a-61 c . The retrievaldevice 3840 is advanced through a microcatheter 3841 inside the arteryand has an activation tether 3844, having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a distal collar 3847, and a ring element 3846 configured at thedistal end of the activation tether 3844. The ring element 3846 isself-expandable from a collapsed configuration to an expandedconfiguration and comprises a radial force that biases the ring element3846 to the expanded configuration. The ring element comprises aplurality of struts 3843. The microcatheter 3841 is retracted and theactivation tether 3844 is manually pulled proximally to compress thedevice proximally and allow ring elements 3842 to reach the expandedconfiguration.

FIGS. 63 a-63 b shows a mechanical clot retrieval device 3860 of thepresent invention which is a slightly variant embodiment of theretrieval device 3840 as illustrated in FIGS. 62 a-62 b . The retrievaldevice 3862 is advanced through a microcatheter 3861 inside the arteryand has an activation tether 3864 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a distal collar 3867, a ring element 3866 configured at thedistal end of the activation tether 3864, and a pair of removal tethers3862 attached to the ring element 3866 having proximal ends that extendout of the artery. The ring element 3866 is self-expandable from acollapsed configuration to an expanded configuration and comprises aradial force that biases the ring element 3866 to the expandedconfiguration. In the collapsed configuration, the radial force isabsorbed by the microcatheter. The microcatheter 3861 is retracted andthe activation tether 3864 is manually pulled proximally to compress thedevice proximally and allow ring element 3866 to reach the expandedconfiguration.

FIGS. 64 a-64 b shows a mechanical clot retrieval device 3880 of thepresent invention which is a slightly variant embodiment of theretrieval device 3860 as illustrated in FIGS. 63 a-63 b . The retrievaldevice 3882 is advanced through a microcatheter 3881 inside the patientartery and has an activation tether 3884 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a couple of collars 3887, a couple of ring elements 3886configured at the distal end of the activation tether 3884, and a pairof removal tethers 3882 having distal ends attached to the ring element3886 and having proximal attached to the collar 3887. The ring element3886 is self-expandable from a collapsed configuration to an expandedconfiguration and has a radial force that biases the ring element 3886to the expanded configuration. In the collapsed configuration, theradial force is absorbed by the microcatheter 3881. Each ring element3886 comprises a plurality of struts 3883. The microcatheter 3881 isretracted and the activation tether 3884 is manually pulled proximallyto compress the device and to allow ring element 3886 reach the expandedconfiguration.

FIGS. 65 a-65 d illustrates another preferred embodiment of a mechanicalclot retrieval device 3900 a of the present invention. The retrievaldevice 3900 a is advanced through a microcatheter 3901 inside thepatient artery and has a pair of activation tethers 3904 having distalends that extend interior of the artery and proximal ends that extendexterior of the artery, a distal collar 3907, and a plurality of ringelements 3902 configured to the distal end of the activation tether3904. The ring elements 3902 are self-expandable from a collapsedconfiguration 3900 a to an expanded configuration 3900 b and have aradial force that biases the ring elements 3902 to the expandedconfiguration 3900 b. In the collapsed configuration, the radial forceis absorbed by an intravascular microcatheter 3901 through which theretrieval device 3900 a is delivered inside the artery. Each ringelement 3902, comprising a plurality of struts 3903, is connected bybridges 3905. Each strut includes a tether guide tube 3908. The distalend of activation tether is passed through the guide tube 3908. Themicrocatheter 3901 is retracted and the activation tethers 3904 aremanually pulled proximally to compress the device proximally and toallow ring elements 3902 to reach the expanded configuration 3900 b.

FIGS. 66 a-66 c illustrates a mechanical clot retrieval device 3920 a ofthe present invention which is a slightly variant embodiment of theretrieval device shown in FIGS. 61 a-61 c . The retrieval device 3920 ais advanced through a microcatheter 3921 inside the patient artery andhas a pair of activation tethers 3924 having distal ends that extendinterior of the artery and proximal ends that extend exterior of theartery, a distal collar 3927, and a plurality of ring elements 3922configured to the distal end of the activation tether 3824. The ringelements 3922 are self-expandable from a collapsed configuration 3920 ato an expanded configuration 3920 b and comprise a radial force thatbiases the ring elements 3922 in the expanded configuration 3920 b. Inthe collapsed configuration, the radial force is absorbed by anintravascular microcatheter 3921 through which the retrieval device 3920a is delivered inside the artery. Each ring element 3922 comprising aplurality of struts 3923 and a limiting tether 3928 is interconnected bybridges 3925. The microcatheter 3921 is retracted and the activationtether 3924 is manually pulled proximally to compress the device and toallow ring elements 3922 to reach the expanded configuration 3920 b. Thelimiting tether 3928 prevents the ring element from expanding beyond acertain diameter.

FIGS. 67 a-67 b shows a mechanical clot retrieval device 3940 of thepresent invention which is a slightly variant embodiment of theretrieval device 3840 as illustrated in FIGS. 62 a-62 b . The retrievaldevice 3940 is advanced through a microcatheter 3941 inside the patientartery and has an activation tether 3944 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a distal collar 3947, and a ring element 3946 configuredat the distal end of the activation tether 3944. The ring element 3946is self-expandable from a collapsed configuration to an expandedconfiguration and has a radial force that biases the ring element 3946to the expanded configuration. The ring element comprising a pluralityof struts 3943 and a limiting tether 3948. The microcatheter 3941 isretracted and the activation tether 3944 is manually pulled proximallyto compress the device and to allow ring elements 3942 to reach theexpanded configuration.

FIGS. 68 a-68 b shows a mechanical clot retrieval device 3960 of thepresent invention which is a slightly variant embodiment of theretrieval device 3860 as illustrated in FIGS. 63 a -63 b. The retrievaldevice 3962 is advanced through a microcatheter 3961 inside the arteryand has an activation tether 3964 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a distal collar 3967, a ring element 3966 configured at thedistal end of the activation tether 3964, and a pair of removal tethers3962 attached to the ring element 3966 having proximal ends that extendexterior of the artery. The ring element 3966 is self-expandable from acollapsed configuration to an expanded configuration and has a radialforce that biases the ring element 3966 to the expanded configuration.In the collapsed configuration, the radial force is absorbed by themicrocatheter 3961. Each ring element 3966 comprises a plurality ofstruts 3963 and a limiting tether 3968. The microcatheter 3961 isretracted and the activation tether 3964 is manually pulled proximallyto compress the device and allow ring elements 3966 to reach theexpanded configuration.

FIGS. 69 a-69 b shows a mechanical clot retrieval device 3980 of thepresent invention which is a slightly variant embodiment of theretrieval device 3880 as illustrated in FIGS. 64 a-64 b . The retrievaldevice 3980 is advanced through a microcatheter 3981 inside the arteryand has an activation tether 3984 having a distal end that extendsinterior of the artery and a proximal end that extends exterior of theartery, a couple of collars 3987, a couple of ring elements 3986configured at the distal end of the activation tether 3984, and a pairof removal tethers 3982 having distal ends attached to the ring element3986. The ring element 3986 is self-expandable from a collapsedconfiguration to an expanded configuration and has a radial force thatbiases the ring element 3986 to the expanded configuration. In thecollapsed configuration, the radial force is absorbed by themicrocatheter 3981. Each ring element comprises a plurality of struts3983 and a limiting tether 3988. The microcatheter 3981 is retracted andthe activation tether 3984 is manually pulled proximally to compress thedevice and allow the ring elements 3986 reach the expandedconfiguration.

The ring elements used in the above description are made of shape-memorymaterial, preferably Nitinol. Remaining elements of the retrieval deviceas described herein are preferably formed of a material such as astainless steel, a nickel-based super alloy, a spring steel alloy,particularly a composition sold under the trademark nitinol.

It will be apparent from the foregoing description that, whileparticular embodiments of the present invention have been illustratedand described, various modifications can be made without departing fromthe spirit and scope of the invention.

Modifications and additions can be made to the various embodiments ofthe invention described herein. For example, while embodiments may referto particular features, the invention includes embodiments havingdifferent combinations of features. The invention also includesembodiments that do not include all of the specific features described.

The invention is not limited to the embodiments hereinbefore describedwhich may be varied in construction and detail.

What is claimed is:
 1. A clot retrieval device for removing a clot froma blood vessel, the clot retrieval device comprising: an elongatemember; a plurality of radial pins disposed along the elongate member;and a plurality of ring elements disposed along the elongate member,wherein the ring elements are self-expandable from a collapsedconfiguration to an expanded configuration, and wherein the ringelements are configured to engage with the radial pins when the ringelements are in the collapsed configuration and disengage from theradial pins when the ring elements are in the expanded configuration. 2.The clot retrieval device of claim 1, wherein the ring elements furthercomprise one or more apices.
 3. The clot retrieval device of claim 2,wherein the one or more apices comprise one or more distal apices andone or more proximal apices offset from the one or more distal apices.4. The clot retrieval device of claim 2, wherein each of the one or moreapices comprises one or more eyelets.
 5. The clot retrieval device ofclaim 4, wherein each eyelet of the one or more eyelets is configured toengage with a respective radial pin of the plurality of radial pins whenthe ring elements are in the collapsed configuration.
 6. The clotretrieval device of claim 5, wherein each eyelet of the one or moreeyelets is configured to disengage from the respective radial pin of theplurality of radial pins when the ring elements are in the expandedconfiguration.
 7. The clot retrieval device of claim 1, wherein the ringelements are connected to the elongate member by one or more tethers. 8.The clot retrieval device of claim 1, wherein the ring elements comprisea radial force configured to bias the ring elements toward the expandedconfiguration.
 9. The clot retrieval device of claim 1, wherein the ringelements are configured to engage the clot when the ring elements are inthe expanded configuration.
 10. A clot retrieval device for removing aclot from a blood vessel, the clot retrieval device comprising: anelongate member comprising a distal end and a proximal end; a pluralityof radial pins disposed along the elongate member; and a plurality ofring elements disposed at the distal end of the elongate member, thering elements comprising: one or more distal apices; and one or moreproximal apices offset from the one or more distal apices, wherein thering elements are self-expandable from a collapsed configuration to anexpanded configuration, wherein the one or more distal apices areconfigured to engage with one or more first radial pins of the pluralityof radial pins when the ring elements are in the collapsed configurationand disengage from the one or more first radial pins when the ringelements are in the expanded configuration, and wherein the one or moreproximal apices are configured to engage with one or more second radialpins of the plurality of radial pins when the ring elements are in thecollapsed configuration and disengage from the one or more second radialpins when the ring elements are in the expanded configuration.
 11. Theclot retrieval device of claim 10, wherein the one or more first radialpins are offset from the one or more second radial pins.
 12. The clotretrieval device of claim 10, wherein each of the one or more distal andproximal apices comprises one or more eyelets.
 13. The clot retrievaldevice of claim 12, wherein: the one or more distal apices areconfigured to engage with the one or more first radial pins via one ormore first respective eyelets of the one or more eyelets, and the one ormore proximal apices are configured to engage with the one or moresecond radial pins via one or more second respective eyelets of the oneor more eyelets.
 14. The clot retrieval device of claim 10, wherein thering elements are connected to the elongate member by one or moretethers.
 15. The clot retrieval device of claim 10, wherein the ringelements comprise a radial force configured to bias the ring elementstoward the expanded configuration.
 16. The clot retrieval device ofclaim 10, wherein the ring elements are configured to engage the clotwhen the ring elements are in the expanded configuration.